Gap Locations Research Articles

Water Enrichment from Pebble Drift in Disks with Gap-forming Planets

Volatiles like H2O are present as ice in solids in the cold outer regions of protoplanetary disks and as vapor in the warm inner regions within the water snow line. Icy pebbles drifting inwards from the outer disk sublimate after crossing the snow line, enriching the inner disk with solid mass and water vapor. Meanwhile, protoplanets forming within the disk open gaps in the disk gas, creating traps against the inward drift of pebbles and in turn reducing water enrichment in the inner disk. Recent disk observations from millimeter interferometry and infrared spectroscopy have supported this broad picture by finding a correlation between the outer radial distribution of pebbles and the properties of inner water vapor spectra. In this work, we aim at further informing previous and future observations by building on previous models to explore pebble drift in disks with multiple gaps. We systematically explore multiple gap locations and their depths (equivalent to the specific masses of planets forming within), and different particle sizes to study their impact on inner disk water enrichment. We find that the presence of close-in deep gaps carved by a Jupiter-mass planet is likely crucial for blocking icy pebble delivery into the inner disk, while planets with lower masses only provide leaky traps. We also find that disks with multiple gaps show lower vapor enrichment in the inner disk. Altogether, these model results support the idea that inner disk water delivery and planet formation are regulated by the mass and location of the most massive planets.

Exploring the potential of forest snow modeling at the tree and snowpack layer scale

Abstract. Boreal and sub-alpine forests host seasonal snow for multiple months per year; however, snow regimes in these environments are rapidly changing due to rising temperatures and forest disturbances. Accurate prediction of forest snow dynamics, relevant for ecohydrology, biogeochemistry, cryosphere, and climate sciences, requires process-based models. While snow schemes that track the microstructure of individual snow layers have been proposed for avalanche research, so far, tree-scale processes resolving canopy representations only exist in a few snow-hydrological models. A framework that enables layer- and microstructure-resolving forest snow simulations at the meter scale is lacking to date. To fill this research gap, this study introduces the forest snow modeling framework FSMCRO, which combines two detailed, state-of-the art model components: the canopy representation from the Flexible Snow Model (FSM2) and the snowpack representation of the Crocus ensemble model system (ESCROC). We apply FSMCRO to discontinuous forests at boreal and sub-alpine sites to showcase how tree-scale forest snow processes affect layer-scale snowpack properties. Simulations at contrasting locations reveal marked differences in stratigraphy throughout the winter. These arise due to different prevailing processes at under-canopy versus gap locations and due to variability in snow metamorphism dictated by a spatially variable snowpack energy balance. Ensemble simulations allow us to assess the robustness and uncertainties of simulated stratigraphy. Spatially explicit simulations unravel the dependencies of snowpack properties on canopy structure at a previously unfeasible level of detail. Our findings thus demonstrate how hyper-resolution forest snow simulations can complement observational approaches to improve our understanding of forest snow dynamics, highlighting the potential of such models as research tools in interdisciplinary studies.

Soil Fungal Function Centralization Enhances the Decomposition of Fine Roots at Canopy Gap Borders

Canopy gaps can result in abiotic heterogeneities and diverse niches from gap borders to centers, potentially affecting fine root decompositions mediated by soil fungal communities. Despite extensive discussions on the relationship between soil fungi and fine root decomposition, the mechanism by which gap locations regulate fine root decomposition through the soil fungal community remains elusive. Here, we conducted an in situ field decomposition experiment of Chinese Toon (Toona senensis) fine roots in a low-efficiency weeping cypress (Cupressus funebris) plantation forest across three microhabitats: gap centers, gap borders, and closed canopy areas. Soil fungal communities were determined using internal transcribed spacer (ITS) sequencing after two years of field incubation. Results showed that soil properties and nutrient content in residual roots varied across the three microhabitats, with the gap borders exhibiting the highest decomposition rates. While fungal α-diversity remained relatively consistent, taxonomic compositions differed significantly. Decomposition rates did not show significant correlations with soil properties, observed fungal ASVs, or overall community composition. However, they positively correlated with the relative abundance of saprotrophic Sordariomycetes, which in turn positively correlated with soil total nitrogen (with a highest correlation), peaking at the gap borders. Overall community variations were primarily driven by soil temperature and magnesium content in residual roots. Further analysis revealed high fungal community similarities and low dispersal limitations between the gap borders and closed canopy areas, with more phylogenetically clustered communities at the borders. These results demonstrate that the gap borders possess a high decomposition rate, likely due to the centralization of functions driven by soil fungi such as saprotrophs existing in the “microbial seed bank” or migrating from closed canopy areas. These findings highlight the key role of soil fungi, especially saprotrophic fungi, in fine root decomposition at the gap borders, stressing the importance of soil fungi-driven mechanisms in nutrient cycling, and also informing sustainable forest management practices.

Durability of pulmonary vein isolation after radiofrequency-balloon ablation

Abstract Aims Recently a multi-electrode radiofrequency balloon (RFB) for pulmonary vein isolation (PVI) was introduced. To the best of our knowledge no data on PVI durability has yet been published. Objectives The aim of this single-center study was to investigate the incidence of pulmonary vein (PV) reconnectionafter RFB-guided PVI. Methods Patients undergoing second ablation for recurrent atrial tachyarrhythmia (ATa) following the initial RFB-PVI were investigated. Left arial (LA) electroanatomic mapping was used. The rate of PV reconnection, the type of recurrent ATaand procedural data were analyzed. Results Among 178 patients treated with RFB, 21 patients underwent a second procedure 11 ± 6 months after the initial PVI. 67% of these patients presented with atrial fibrillation (AF), 33% with atrial tachycardia. Regarding baseline characteristics, 71% of these patients were male, mean age was 67±10, mean BMI was 28±5, 67% had hypertension and 33% had coronary artery disease. Overall, 83 PVs including one left common PV (LCPV) were assessed. The rate of PV reconnection was 28% (23/83 PVs). 57% of patients (12/21) had at least one reconnected PV. Patient with PV-reconnection had more AF recurrence and less often atrial tachycardia (AT) (AF: 75%, AT: 25%) than patients with durably isolated PVs (AF: 56%, AT: 44%). Most reconnections were detected in septal PVs. Reconnections were distributed as follows: RIPV: 8/21, RSPV: 7/21, LIPV: 5/20, LSVP: 3/20, LCPV: 0/1. Precise localization of the gaps could be identified in 15/23 PVs. Most common gap locations were at the anterior carina (4/15) for septal PVs and anterior-inferior (3/15) at the LIPV. Ablation strategy was pure PV reisolation in 8/12 patients and PV reisolation with additional linear lesions in 4/12 patients. All patients with durably isolated PVs were treated with additional substrate modification. In total, following additional lesions were set: anterior line: 6, roof line: 11, cavotricuspid isthmus (CTI): 7, LAA-Isolation: 1, free wall of the right atrium: 1. Regarding procedural data of the index procedure, the number of applications was not a statistically significant predictor of reconnection (p=0.77). Conclusion We provide the first insight into durability of PVI after radiofrequency-balloon ablation. 72% of all PVs were still isolated. Our data on gap localization might help to identify regions where optimal balloon contact is difficult to achieve. More data on this topic might reveal predictors for PV reconnections.

Pipeline inertial measurement mileage correction method based on pipeline junction detection

A pipeline measurement robot(PMR) is an important tool for pipeline shape measurement and disease detection. Flexible pipelines in the horizontal plane inside dams are used for internal deformation monitoring, which is characterized by small caliber, no ground marking assistance, and higher accuracy requirements, so the accuracy of the data fusion algorithm needs to be improved. In this paper, we propose a pipeline inertial measurement odometry correction method based on pipeline junction detection, which establishes a reference model of pipeline junction locations, detects pipeline junction gap locations along the measurement route using k-mean clustering, corrects odometer data based on the difference between the detected and reference locations, fuses IMU and odometer data and evaluates the internal compliance accuracy. The proposed method is validated using the measured data of the internal pipeline of Tianchi Dam, and the results show that the method proposed in this paper reduces the root-mean-square error (RMSE) by about 46% compared with the results without detection correction and direct fusion. Therefore, the method has good results and practical applications.

Assessing mammal fence crossing and local fence management in relation to classical swine fever spread in Japan.

Infectious diseases at the wildlife-livestock-human interface have become a crucial issue, and evidence-based measures are growing increasingly important. One countermeasure against animal diseases in wildlife is using fencing to contain and reduce disease spread and transmission rates between wild populations; however, quantitative assessments on fencing are rare. Moreover, existing research on fencing has highlighted knowledge gaps on the social and ecological aspects relevant to the use and design of fences. To control the spread of classical swine fever, fences were installed from the east to west in Gifu Prefecture, Japan, by March 2019, with the aim of restricting wild boar movement. To clarify the process of installation and maintenance of the fences, we conducted semi-structured interviews with prefectural government officers in Gifu Prefecture. Additionally, we installed infrared-triggered cameras at fence locations with and without gaps to evaluate the fence permeability of mammals. We used a generalized linear mixed model to evaluate the relationship between the presence of gaps and the relative abundance and permeability of each mammal. Our findings showed that the occurrence of gaps was inevitable during the installation and management of wide-area perimeter fence in Japan, partly because of social factors. For example, fences could not be installed on roads that were frequently used by residents and were not adequately maintained owing to budgetary reasons in some cases. Analysis of footage from the infrared-triggered cameras revealed that several mammal species crossed the fence at gaps and even had the ability to cross the gapless parts of the fences. Wild boars crossed through the gaps regularly. It is possible that Sika deer, Japanese serows, raccoons, Japanese badgers, raccoon dogs, Japanese macaques, and feral cats crossed through fence gaps because their relative abundance was high at gap locations. In contrast, Japanese hares slipped through the fence mesh rather than crossing through the gaps. In conclusion, we suggest that coordination and collaboration among related parties, a sufficient supply of fence materials, and securing a budget for fence maintenance are important for fence installation and maintenance. Furthermore, as fence gaps are inevitable, technical development of countermeasures for these gaps could be effective.

Sex Differences in Axonal Dynamic Responses Under Realistic Tension Using Finite Element Models.

Existing axonal finite element models do not consider sex morphological differences or the fidelity in dynamic input. To facilitate a systematic investigation into the micromechanics of diffuse axonal injury, we develop a parameterized modeling approach for automatic and efficient generation of sex-specific axonal models according to specified geometrical parameters. Baseline female and male axonal models in the corpus callosum with random microtubule (MT) gap configurations are generated for model calibration and evaluation. They are then used to simulate a realistic tensile loading consisting of both a loading and a recovery phase (to return to an initial undeformed state) generated from dynamic corpus callosum fiber strain in a real-world head impact simulation. We find that MT gaps and the dynamic recovery phase are both critical to successfully reproduce MT undulation as observed experimentally, which has not been reported before. This strengthens confidence in model dynamic responses. A statistical approach is further employed to aggregate axonal responses from a large sample of random MT gap configurations for both female and male axonal models (n = 10,000 each). We find that peak strains in MTs and the Ranvier node and associated neurofilament failures in female axons are substantially higher than those in male axons because there are fewer MTs in the former and also because of the random nature of MT gap locations. Despite limitations in various model assumptions as a result of limited experimental data currently available, these findings highlight the need to systematically characterize MT gap configurations and to ensure a realistic model input for axonal dynamic simulations. Finally, this study may offer fresh and improved insight into the biomechanical basis of sex differences in brain injury, and sets the stage for more systematic investigations at the microscale in the future, both numerically and experimentally.

Using barrier-adjacent measurements and predictions to determine effects of small gaps in highway noise wall

Noise walls are installed along highways to reduce highway traffic noise in adjacent communities. Based on installation or aging effects, some noise walls contain small gaps between panels. Applying traditional barrier insertion loss measurements comparing sections with and without gaps may not be possible due to site conditions. For this study, barrier-adjacent sound levels were collected at gap locations and comparable reference (non-gap) locations to determine the gap effect immediately behind the barrier. Two methods are then applied to determine how these gap effects translate to nearby communities. Both broadband and spectral sound levels are analyzed to determine that the effects of a small gap (up to 0.5 inches in height and 10 inches in length) can be up to 2 dB near the barrier but diminish rapidly with distance.

AB-452663-2 LEFT ATRIAL BOX ISOLATION GUIDED BY FORCE-POWER-TIME FORMULA (ABLATION INDEX): HIGH PREVALENCE OF EPICARDIAL CONDUCTION VIA SEPTOPULMONARY BUNDLE IN ATRIAL FIBRILLATION PATIENTS

Circumferential, continuous, transmural atrial lesions are desired to facilitate pulmonary vein (PV) isolation. However, atrial wall thickness around the PV is variable (5-6 mm in the superior/anterior segments and 2-4 mm in the inferior/posterior segments). Previous experimental studies have shown that radiofrequency (RF) lesion depth and diameter can be predicted by a logarithmic formula using contact force (CF), RF power and application time (Force-Power-Time Formula, Ablation Index, AI). The purpose of this study was to test the ability of AI guided ablation to achieve left atrial (LA) box isolation by a single RF encirclement and examine the location of residual conduction (gap) within the box in patients with atrial fibrillation (AF). In 42 patients with AF, LA box isolation was performed using a 7.5Fr CF catheter (ThermoCool SmartTouch SF, Biosense Webster) and CARTO system. Using RF power (35-40Watts) and CF (5-45g), a target AI value of 380-400 was used for posterior/inferior segments with an inter-lesion distance (ILD) of 4mm and a target AI value of 550-600 for anterior/superior/septal segments with an ILD of 6mm along the box circumference (Figure). RF was delivered until AI reached target values or terminated prematurely when esophageal temperature reached <38.5°C. After the first encirclement along the box line, activation mapping was performed to confirm box isolation and identify gap locations. Total RF time for box isolation was 27.2±4.6 min and box circumference length was 21.2±2.5 cm. Complete box isolation was obtained by the first encirclement in 17/42 (40%) pts. In the remaining 25/42 (60%) pts, activation mapping within the box lesion set identified earliest atrial activation along the ablation line in only 4/42 (10%) pts (indicating endocardial gaps), whereas activation mapping within the box identified earliest atrial activation at a site distant from the ablation line in 21/42 (50%) pts, suggesting epicardial conduction through a septopulmonary bundle (Figure). Focal ablation at endocardial gaps along the ablation line or at the epicardial focal breakouts within the box resulted in compete box isolation in all 25 pts. LA box isolation guided by AI effectively prevented endocardial gaps along the ablation line. However, epicardial conduction via a septopulmonary bundle was often observed (50%).

Legacy effects of canopy gaps on liana abundance 25 years later in a seasonal tropical evergreen forest in northeastern Thailand

AbstractLianas require host trees to reach and stay in the forest canopy, but as seedlings and juveniles, they benefit from canopy gaps created by treefalls. Here, we evaluated the relative importance of these two aspects, that is, the availability of potential hosts vs. the legacy effect of past treefall gaps, on the local abundance of liana stems in a seasonal tropical evergreen forest in the Sakaerat Biosphere Reserve in northeastern Thailand. Within a 2.5‐ha plot for forest dynamics monitoring, canopy height was measured in 1993 and 2018 at 5‐m intervals to distinguish areas of mature (canopy height ≥ 20 m), building (10–20 m), and gap phases (&lt; 10 m). In 2017–2018, we surveyed all liana stems ≥ 1 cm in diameter at breast height within 50 subplots (10 m × 10 m each) and recorded their diameter and the diameter of the host tree. Of a total of 445 liana individuals, 242 could be identified at least to the family level, while the others had clear morphological traits of climbing mechanisms. The number of liana stems was higher in areas that had been at the building/gap phase than those at the mature phase in 1993. When this 25‐year‐old legacy of past gap locations was considered, there was a positive association of local abundance between lianas and trees in areas at the mature phase in 2018. In conclusion, liana abundance reflected a long‐term legacy of past treefall gaps more than 25 years earlier in this seasonal evergreen forest.

Reconstruction of the gaps in malfunction Landsat7 images: Review

The Landsat satellite series program has been developed and managed by the United States Geological Survey (USGS) since 1972, representing the longest temporal record of space-based terrestrial observation and taking into account the primary forces advancing the science concept in the global earth systems. Despite the malfunction images of Landsat 7 in 2003, the malfunction imagery preserves its important value in both technical studies and applications. Thus, there are numerous approaches and algorithms that have been presented to solve the SLC-off trouble by finding appropriate methods and approaches to predict the pixel reflectance values at gap locations accurately. This work aims to familiarize the reader with the concepts related to recovering the gap locations of the Landsat 7 SLC-off imagery approaches.

Analysing gap dynamics in forest canopies with landscape metrics based on multi-temporal airborne laser scanning surveys – A pilot study

For a long time gaps or openings in the forest canopy have been of considerable interest to forest ecologists and to forest managers. In the context of disturbances induced by climate change, canopy gap dynamics are of particular interest, since they can indicate imminent damage to forest resources and irreversible trends such as forest decline. Here, statistical significance is crucial for establishing whether any imminent large-scale threat to the sustainability of forest resources exists. In order to be able to assess significance, we applied the Boolean model, a null or reference model from random set statistics. The Boolean model served as a theoretical benchmark for testing the significance of the observed trends in forest canopy gap dynamics. As a pilot study we analysed airborne laser scan (ALS) data collected in the Krycklan catchment area (Northern Sweden) in 2006 and 2015. The data were analysed using eight different landscape metrics. Despite the moderate resolution of our ALS data the landscape metrics have proved to be useful tools for monitoring canopy gap dynamics of forest ecosystems. The Boolean model has been successful in ascertaining statistical significance and the model parameters indicated important trends. In the Krycklan catchment area, there was no significant trend of canopy gap dynamics indicating any harmful development between 2006 and 2015. On the contrary, we found evidence for gaps closing in and gap locations becoming more random whilst the canopy cover increased between the two survey years.

Effect of gap-filling technique and gap location on linear and nonlinear calculations of motion during locomotor activities

BackgroundMarker occlusion during camera-based movement analysis is common. Different interpolation techniques are available for estimating location of missing marker trajectories. Research questionWhat is the effect of gap location and interpolation technique on linear and nonlinear measures for a given kinematic time series? MethodsKinematic data were recorded during motor-assisted elliptical training and treadmill walking. Gap-filling techniques (i.e., Cubic, Makima, Autoregressive, Nearest Neighbor, and No Interpolation) and gap locations experimentally applied to each cycle across initially complete time series (Gap 1: local minimum and maximum peaks; Gap 2: maximum peaks; Gap 3: maximum peaks at negative slope; Gap 4: random locations) were examined during linear (Maxima and Minima joint angles) and nonlinear [maximum Lyapunov exponent (LyE)] measures. ResultsGap-filling technique and gap location influenced values calculated for linear and nonlinear measures of joint motions. When referenced to the gold standard (original data series without gaps), across all joints studied the average % error of Maxima and Minima joint angles and LyE % error were lower when applying Cubic, Makima, Autoregressive, and Nearest Neighbor techniques compared to No Interpolation (p < 0.0001). The % error of Maxima joint angles was lower for Gaps 1, 3, and 4 compared to Gap 2 (p = 0.0003), while % error of Minima joint angles was lower for Gaps 2 and 3, compared to Gaps 1 and 4 (p < 0.0001). An interaction between gap-filling technique and gap location was identified for LyE % error, in which Gap 4 % error was significantly greater during No Interpolation compared to other gap-filling techniques (p < 0.0001). SignificanceFindings can guide selection of appropriate techniques to manage missing kinematic data points in camera-based motion analysis time series. Gap-filling techniques significantly reduced error in calculating select linear and nonlinear measures of variability, with Cubic most consistently resulting in the greatest reduction in error.

柏木人工林林窗位置对香椿细根分解及土壤真菌群落多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 柏木人工林林窗位置对香椿细根分解及土壤真菌群落多样性的影响 DOI: 10.5846/stxb202101210225 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2017YFD0600302-05）；国家自然科学基金项目（32071747）；绵阳师范学院生态安全与保护四川省重点实验室开放基金项目（ESP-2104）；绵阳师范学院高层次人才科研启动项目（QD2020A17） Effects of gap locations on the decomposition of fine root of Toona sinensis and soil fungal community diversity in cypress plantation forest Author: Affiliation: Fund Project: The Key Program of the Chinese Academy of Sciences 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了解林窗位置对香椿细根分解及土壤真菌群落多样性的影响，以川中丘陵区30a生柏木人工林为研究对象，采用Illumina Miseq高通量测序技术研究200 m2人工林窗中心位置（GC）、边缘位置（GB）、郁闭林（CC）对香椿细根2a自然分解后土壤真菌群落结构及多样性的影响。结果表明，林窗内不同位置之间微环境差异显著（P<0.05），土壤理化性质对林窗位置变化的响应较细根养分元素更积极，GB位置细根分解速率显著高于GC和CC。土壤真菌门水平在3个林窗位置间无显著差异，其中子囊菌门、担子菌门是优势类群；腐生营养型真菌在3个林窗位置上具有显著差异，散囊菌目、粪壳菌目、肉座菌目、刺盾炱目、伞菌目是3个位置上相对丰度值>1%的优势类群，刺盾炱目、伞菌目相对丰度在GB和CC之间有显著差异（P<0.05）；青霉属和曲霉属是真菌在属水平上的优势类群，其相对丰度在3个位置间有极显著差异（P<0.01）。林窗位置未对真菌群落α多样性产生显著影响，但群落β多样性对位置变化的响应显著。GB位置群落β多样性显著高于GC和CC （P<0.05），共有种数量最多，GC位置特有种数量最多。冗余分析发现较多环境因子对真菌群落的影响显著（P<0.01），Mantel test （和partial Mantel test）分析结果表明土壤pH值、土壤含水量、土壤温度、土壤速效磷、土壤全氮是真菌群落多样性的重要影响因子。综上所述，林窗内位置对土壤真菌类群构成和群落β多样性具有差异性影响，在柏木人工林内实施林窗式干扰有助于调节细根分解等地下生态进程。 Abstract:The effect of gap location heterogeneity on decomposition of plant fine roots and soil fungal community diversity was investigated in a forest with Cupressus funebris plantation for 30 years, in the hilly region in central Sichuan Province. In an area with gap size 200 m2, the structure and diversity of soil fungal community associated with 2a natural decomposition of fine root of Toona sinensis were investigated separately on three different locations:gap center (GC), gap boarder (GB) and closed canopy (CC), by using Illumina MiSeq high-throughput sequencing technology. The results showed that there were significant differences in microenvironment across different gap locations (P<0.05). The response of soil physical and chemical properties to the gap position was more sensitive than that of fine root nutrient elements, and the decomposition rate of fine roots at GB position was significantly higher than that of GC and CC. There was no significant difference in soil fungal community at phylum level. Ascomycetes and Basidiomycetes were dominant groups across different gap locations. Base on FUNGuild results, the trophic modes of saprotrophs showed significant differences across different gap locations, the classes of Eurotiales, Hypocreales, Sordariales, Chaetothyriales and Agaricales were dominant with the relative abundances>1% across the three locations. The relative abundances of Agaricales and Chaetothyriales were significantly different between GB and CC (P<0.05). The genera of Penicillium, Aspergillus, Chaetomium and Staphylotrichum were the dominant taxa, and there were significant differences in their relative abundances across the three locations (P<0.01). The α diversities of the fungal communities were not significantly affected by the gap locations, but their β diversities were more responsive to different gap locations. The β diversity at GB was significantly higher than those at GC and CC (P<0.05), with the largest number of shared species at GB and the largest number of endemic species at GC site. Redundancy analysis revealed significant effects of the environmental factors on the fungal community (P<0.01). Partial Mantel test showed that the factors such as pH, water content (SWC), temperature (ST), available P (SNP) and total N (STN) in soil were important factors influencing fungal community diversity. In conclusion, forest gap locations significantly affected the composition and diversity of soil fungal community. The findings were helpful to regulate the underground ecological processes such as fine root decomposition in cypress plantation forests. 参考文献 相似文献 引证文献

Genomic landscape of single-stranded DNA gapped intermediates in Escherichia coli.

Single-stranded (ss) gapped regions in bacterial genomes (gDNA) are formed on W- and C-strands during replication, repair, and recombination. Using non-denaturing bisulfite treatment to convert C to U on ssDNA, combined with deep sequencing, we have mapped gDNA gap locations, sizes, and distributions in Escherichia coli for cells grown in mid-log phase in the presence and absence of UV irradiation, and in stationary phase cells. The fraction of ssDNA on gDNA is similar for W- and C-strands, ∼1.3% for log phase cells, ∼4.8% for irradiated log phase cells, and ∼8.5% for stationary phase cells. After UV irradiation, gaps increased in numbers and average lengths. A monotonic reduction in ssDNA occurred symmetrically between the DNA replication origin of (OriC) and terminus (Ter) for log phase cells with and without UV, a hallmark feature of DNA replication. Stationary phase cells showed no OriC → Ter ssDNA gradient. We have identified a spatially diverse gapped DNA landscape containing thousands of highly enriched ‘hot’ ssDNA regions along with smaller numbers of ‘cold’ regions. This analysis can be used for a wide variety of conditions to map ssDNA gaps generated when DNA metabolic pathways have been altered, and to identify proteins bound in the gaps.

Two-Channel VO2 Memory Meta-Device for Terahertz Waves.

Vanadium oxide (VO2), as one of the classical strongly correlated oxides with a reversible and sharp insulator-metal transition (IMT), enables many applications in dynamic terahertz (THz) wave control. Recently, due to the inherent phase transition hysteresis feature, VO2 has shown favorable application prospects in memory-related devices once combined with metamaterials or metasurfaces. However, to date, VO2-based memory meta-devices are usually in a single-channel read/write mode, which limits their storage capacity and speed. In this paper, we propose a reconfigurable meta-memory based on VO2, which favors a two-channel read/write mode. Our design consists of a pair of large and small split-ring resonators, and the corresponding VO2 patterns are embedded in the gap locations. By controlling the external power supply, the two operation bands can be controlled independently to achieve at least four amplitude states, including “00”, “01”, “10”, and “11”, which results in a two-channel storage function. In addition, our research may provide prospective applications in fields such as THz switching, photon storage, and THz communication systems in the future.

Molecules with ALMA at Planet-forming Scales (MAPS). V. CO Gas Distributions

Abstract Here we present high-resolution (15–24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs observations of the (J = 2–1) and (1–0) lines of 13CO and C18O and the (J = 1–0) line of C17O for five protoplanetary disks. We retrieve CO gas density distributions, using three independent methods: (1) a thermochemical modeling framework based on the CO data, the broadband spectral energy distribution, and the millimeter continuum emission; (2) an empirical temperature distribution based on optically thick CO lines; and (3) a direct fit to the C17O hyperfine lines. Results from these methods generally show excellent agreement. The CO gas column density profiles of the five disks show significant variations in the absolute value and the radial shape. Assuming a gas-to-dust mass ratio of 100, all five disks have a global CO-to-H2 abundance 10–100 times lower than the interstellar medium ratio. The CO gas distributions between 150 and 400 au match well with models of viscous disks, supporting the long-standing theory. CO gas gaps appear to be correlated with continuum gap locations, but some deep continuum gaps do not have corresponding CO gaps. The relative depths of CO and dust gaps are generally consistent with predictions of planet–disk interactions, but some CO gaps are 5–10 times shallower than predictions based on dust gaps. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.

An optimization problem for maximum vibration suppression in reconfigurable one dimensional metamaterials

Acoustic metamaterials have already been shown to be effective for vibration reduction and control. Local resonances in the metamaterial cause waves at frequencies within band gaps to become evanescent, thus preventing wave propagation through the material. Active and adaptable local resonances enables the band gaps to be shifted in frequency and increased in bandwidth. Since metamaterial local resonances are usually composite, methods to specify optimal component configurations are helpful for passive metamaterials and almost necessary for adaptable metamaterials, where the metamaterial must be reconfigured for optimal performance at various frequency ranges. To assess band gap locations and bandwidths for metamaterials, a wavenumber spectrum is commonly computed. Commonly, a parameter study of adaptable unit cell variables will be performed to assess optimal configurations of adaptable metamaterials. In this paper, the complex wavenumber is proposed as a direct optimization objective for reconfiguration of active adaptable acoustic metamaterials for maximum vibration suppression at a frequency range of choice. By directly maximizing the imaginary part of the wavenumber, associated with wave attenuation, the unit cell configuration maximum vibration suppression can be obtained for an operating frequency of choice. Additionally, since the optimization problem requires constraints for feasible solutions and the example active piezoelectric metamaterial system shown here is electrically unstable at some configurations, we also explore an experimental method for bounding the optimization problem. Numerical results of the optimization problem are presented.

Superior vena cava isolation using a novel ablation catheter incorporating local impedance monitoring.

A novel technology able to measure the local impedance (LI) during radiofrequency ablation has become available for clinical use. We investigated the change in the LI characteristics during superior vena cava isolations (SVCIs) using a novel catheter equipped with mini-electrodes. Twenty paroxysmal atrial fibrillation patients (68 ± 9 years; 14 males) underwent an SVCI by targeting breakthroughs. Subsequently, dormant conduction provoked by adenosine triphosphate (ATP) was evaluated. Electrical SVCIs were successfully achieved in all with 7.2 ± 3.0 radiofrequency applications (RFA) without any complications. The procedure and fluoroscopic times were 13.1 ± 8.1 and 2.8 ± 2.3 min. No ablation was required at the anteroseptal SVC in 19 (95.0%) patients. The baseline LI and generator impedance (GI) were 125 ± 23 and 105 ± 14Ω. LI drops during RFA were significantly greater than GI drops (17 ± 12 vs. 4 ± 4Ω, p < 0.001). The correlation between the LI drops and GI drops was relatively high (R = 0.69, p < 0.001). LI drops were highest at the septal SVC and lowest at the lateral followed by antero-lateral SVC. The baseline electrogram amplitude between the mini-electrodes and tip-ring electrodes was 1.2 ± 1.4 and 0.8 ± 0.6 mV. The mini-electrode amplitude is more sharply attenuated with a greater magnitude than the tip-ring amplitude (p < 0.001). ATP-provoked dormant conduction was exposed in 10/17 (58.8%) patients and antero-lateral SVC gap locations in 7. Antero-lateral SVC LI drops were similar between patients with and without dormancy. The LI drop magnitude during RFA significantly differed among the SVC segments. Antero-lateral SVC ATP-provoked dormant conduction was often exposed, and additional applications are recommended following the isolation for a robust SVCI.

Quantitative Analysis of Electrode Gaps in Prismatic Format Lithium-Ion Cells

Inside a lithium-ion cell, many layers of positive and negative electrodes are separated by an electrolyte-soaked separator. The positive and negative electrodes are engineered to be parallel so that the current distribution is uniform between each set of electrodes. This uniform current density further leads to uniform and predictable operation of the cell. During manufacturing, gaps can be introduced between the electrode layers. This is especially prevalent in prismatic cells because the cell manufacturing process involves inserting the pliable cell windings into a rigid cell housing and applying vacuum during electrolyte filling. These electrode gaps lead to non-uniform current densities, resulting in adverse effects such as incomplete lithiation, electrolyte degradation and possibly lithium plating.One method of non-destructively visualizing internal cell features is computed tomography (CT) scanning. Collecting data via this method is relatively fast with a typical cell scan takes ~1 hr and multiple cells being scanned at once. The output is commonly a set of 16-bit .tiff images that can be loaded and analyzed by a variety of software packages, with Volume Graphics Studio and Avizo being two common programs. These programs can be used to make a variety of measurements on individual datasets, but they lack the ability to conduct high-throughput analysis of many datasets.In this work, we have collected computed tomography data on prismatic cells cycled at a series of temperatures throughout their cycle life of up to 500 cycles. This data is analyzed for electrode gap features using a python code written to extract the number of gaps, gap locations, and gap volume for each dataset. This data is then aggregated for all datasets and analyzed for macroscopic trends. One finding from the study is that cells cycled at lower temperatures showed less expansion/contraction because of kinetics and less capacity passed overall, while cells cycled at higher temperatures showed increased gap volume due to material growth between layers. Additional findings and opportunities for future work will be presented. Image upload: Horizontal mapping of gap locations in individual cells from the three different temperature groups, where the size of the bubble correlates to the size of the gap. (0 Cycles: yellow, 100 & 200 cycles: blue, 500 cycles: purple) Figure 1