Cold Regions Science and Technology最新文献

{"title":"Mechanical properties of Inuvik-Tuktoyaktuk highway built on permafrost over the years of operation from 2019 to 2024","authors":"Farshad Kamran ,&nbsp;Jean-Pascal Bilodeau ,&nbsp;Eileen Catalina Castilla Duarte ,&nbsp;Simon Dumais ,&nbsp;Guy Doré","doi":"10.1016/j.coldregions.2026.104855","DOIUrl":"10.1016/j.coldregions.2026.104855","url":null,"abstract":"<div><div>Road infrastructure built over permafrost is increasingly vulnerable to climate change, with seasonal thawing causing significant degradation in mechanical performance. Variations in moisture content, active layer thickness, and freeze-thaw cycles can compromise structural integrity, especially in granular embankments without asphalt surfacing. Understanding how these environmental changes affect stress distribution and stiffness is critical for maintaining long-term road stability in northern regions. This study monitored the mechanical response of a granular road embankment along a permafrost-affected corridor during the thawing seasons of 2022 and 2024. Field instrumentation, including pressure cells and strain gauges installed in site, captured stress and deformation data under controlled truck loading at multiple speeds. Seasonal site visits were conducted in June, August, and September each year. Elastic modulus was calculated from stress–strain relationships and interpreted alongside temperature and moisture content profiles obtained during testing. The results revealed strong seasonal trends: in 2022, the modulus increased from 86.3 MPa in June to over 300 MPa in September, indicating progressive stiffening as the embankment dried. In 2024, modulus values were significantly lower across all months, suggesting deeper thaw penetration and a weaker subgrade layer. Higher stress magnitudes and pulse widths in August reflected dry, compacted conditions, while June responses showed energy dissipation in wetter, softer soils. These findings demonstrate the impact of permafrost degradation on embankment stiffness and stress transmission, emphasizing the need for improved monitoring and design adaptations in cold regions.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104855"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observations and modeling of slushflows from Atigun Pass, Alaska","authors":"Lars Blatny ,&nbsp;David Hamre ,&nbsp;Johan Gaume ,&nbsp;Peter Gauer ,&nbsp;Arthur Mears","doi":"10.1016/j.coldregions.2025.104812","DOIUrl":"10.1016/j.coldregions.2025.104812","url":null,"abstract":"<div><div>Slushflows consist of a mixture of snow, water, and ice and often entrain debris or sediments. The high mobility and high density of the flows make them a considerable natural hazard, endangering settlements and infrastructure. They are most commonly associated with higher latitudes, such as Norway, Iceland, or Alaska, but have also been reported in various other countries, including regions such as the Alps. This paper describes slushflows near Atigun Pass, Alaska, which were well documented in a study for the Alyeska Pipeline Service Company (APSC) in 1982. The information has been privately held and is now being released for research purposes. Moreover, state-of-the-art modeling techniques are introduced and applied to the described slushflows, considering both depth-averaged and depth-resolved (three-dimensional) numerical methods with viscoplastic and elasto-viscoplastic rheological models. The observations and modeling approaches presented in this study provide insights that can improve the understanding and assessment of slushflows and their dynamics.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104812"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of seepage characteristics in frozen-thawed sandstone: Insights from coupled PFC-COMSOL simulations","authors":"Taoying Liu,&nbsp;Sisi Wang,&nbsp;Huaheng Li,&nbsp;Mengyuan Cui","doi":"10.1016/j.coldregions.2026.104844","DOIUrl":"10.1016/j.coldregions.2026.104844","url":null,"abstract":"<div><div>The seepage characteristics of geotechnical materials critically affect the stability of engineering structures under rainfall conditions. In cold and high-altitude regions, repeated freeze-thaw (F-T) cycles cause the internal deterioration and damage of engineering rock masses and alter the seepage behavior, leading to frequent instability hazards. To address this issue, a series of F-T tests were conducted on sandstone samples to investigate the evolution of rock's porosity and permeability subjected to different F-T cycles in this paper, combining with the coupled PFC-COMSOL numerical simulations. Moreover, the Dual Permeability Model (DPM) was further employed to simulate the effects on rainwater infiltration behaviors of sandstone treated with F-T cycles. The results show that the porosity of sandstone decreases slowly first and then increases rapidly with the increase of F-T cycles. The permeability exhibits a significant positive correlation with the number of F-T cycles. The peak position of seepage pressure moves deeper into the rock mass with increasing F-T cycles, and the evolution trend of seepage pressure in different seepage media is synchronous. In addition, the influence of F-T cycles on the wetting-front depth is more pronounced than that of rainfall intensity, with an average increase of approximately 30% as the number of cycles rises. During the rainfall infiltration, a dynamic negative correlation between seepage pressure and effective saturation is observed. These test findings demonstrate that F-T cycling significantly modifies the rock pore structure and enhances its infiltration capacity. The study results provide a theoretical reference for the design of protective and drainage systems and for the stability assessment of geotechnical works in alpine and seasonally frozen regions.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104844"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review of ice accretion, detection, and mitigation methods for the gondola infrastructure application","authors":"Hamza Asif,&nbsp;Muhammad S. Virk,&nbsp;Jan-Arne Pettersen,&nbsp;Pourya Pourhejazy","doi":"10.1016/j.coldregions.2026.104847","DOIUrl":"10.1016/j.coldregions.2026.104847","url":null,"abstract":"<div><div>Despite the vast economic (e.g., tourism) and environmental advantages (e.g., clean transportation) of gondola lifts, there is a lack of a comprehensive reference about ice accretion, ice detection, and mitigation solutions for safe operations of gondola infrastructure. This paper presents a state-of-the-art scientific literature review drawn from synergetic applications (e.g., power transmission lines, railways, bridges, and aviation structures) to investigate and identify the scientific technological knowledge gaps. An overview of gondola system components along with their operations, as well as the system components' design and safety standards, is provided to discuss the potential impacts of icing on gondola infrastructure. The literature review revealed a lack of comprehensive scientific studies explicitly addressing ice accretion on gondola systems. Insights from the comparable applications and discussion with the gondola operators indicate that ice accretion can pose significant safety risks and potential structural failures. Using opinion and critical reasoning from experts, some existing suitable ice detection and mitigation techniques are listed and mapped to critical gondola components with the potential for practical implementation. Several directions for future research are also identified to contribute to this underexplored field of research.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104847"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Freeze-thaw damage differences in saturated limestone: Macro-meso-micro response and mechanism driven by initial properties","authors":"Wen Zhang,&nbsp;Chengxing Chai,&nbsp;Huie Chen,&nbsp;Shurui Zhang,&nbsp;Hua Du,&nbsp;Jia Wang,&nbsp;Han Yin,&nbsp;Jian Wang,&nbsp;Danyang Wu","doi":"10.1016/j.coldregions.2026.104849","DOIUrl":"10.1016/j.coldregions.2026.104849","url":null,"abstract":"<div><div>Rock damage induced by freeze–thaw cycles is influenced by several key factors; however, the underlying mechanisms associated with fissures and mineral composition remain incompletely understood. In this study, four distinct types of limestone specimens, characterized by initial longitudinal wave velocities (<em>V</em>_p) of 1.029 km/s, 3.485 km/s, 4.474 km/s, and 5.556 km/s, underwent 100 freeze–thaw cycles. Through the integration of macroscopic physical testing, CT and SEM microstructural imaging, and XRD mineralogical analysis, the multiscale damage evolution was systematically characterized across these specimens. The results show that progressive freeze–thaw cycles induce concurrent increases in mass loss rate, water absorption rate, and <em>V</em>_p loss rate across all specimens. Specimen P-1 (<em>V</em>_p = 1.029 km/s) exhibited the most substantial mass loss and water absorption, whereas P-3 (<em>V</em>_p = 3.485 km/s) manifested the most pronounced <em>V</em>_p degradation. Comparatively, P-4 (<em>V</em>_p = 4.474 km/s) and P-5 (<em>V</em>_p = 5.556 km/s) displayed progressively attenuated deterioration trends. Microstructural analysis via CT and SEM identified the most extensive micro-crack propagation in P-3. XRD quantification further revealed a consistent mineralogical shift among all specimens after 100 freeze–thaw cycles: decreasing calcite content coupled with increasing clay mineral content, with P-3 undergoing the most pronounced alterations. The study elucidates the distinct freeze-thaw damage mechanisms across three limestone types: low <em>V</em>_p limestone manifested predominant surface spalling and dilation of open cracks; medium <em>V</em>_p limestone exhibited internal micro-crack propagation and transgranular cracking. The degradation of calcite cement reduced structural integrity and promoted microcrack development; high <em>V</em>_p limestone demonstrated exceptional freeze–thaw resistance due to its dense structure and strong cement stability. These findings provide a theoretical basis for stability assessment and hazard mitigation in rock engineering projects in cold regions.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104849"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sea ice thickness surveys with a drone-borne multi-frequency EM sensor","authors":"Mara Neudert ,&nbsp;Carl Thibault ,&nbsp;Robert Briggs ,&nbsp;Trevor Bell ,&nbsp;Christian Haas","doi":"10.1016/j.coldregions.2026.104848","DOIUrl":"10.1016/j.coldregions.2026.104848","url":null,"abstract":"<div><div>Electromagnetic (EM) ice thickness surveys are essential for sea ice thickness monitoring in Arctic communities and a valuable tool for sea ice research, helping mitigate sea ice travel risk by identifying areas with thin ice and assessing ice thickness distributions. Traditionally, the sensor is towed on a sled by a snowmobile for data collection; however, climate change induced variations in ice conditions are making ice travel more hazardous and less predictable. This study examines the use of airborne EM surveys to reduce the need for direct ice access. A lightweight commercial multi-frequency EM sensor combined with custom altitude and attitude sensors were mounted on a custom drone to remotely measure ice thickness, minimizing human risk exposure while potentially expanding the survey range. Challenges included ensuring stable drone performance under sensor load in typical conditions, managing noise and interference in the EM signal created by the drone, and collecting accurate sensor altitude data for precise thickness estimates. Test flights successfully retrieved combined ice and snow thickness in agreement with manual drill hole measurements, and tested an efficient in-flight sensor calibration. Our results are promising, indicating strong potential for efficient and accurate EM surveys from a safe distance of increasingly hazardous ice using a drone-borne multi-frequency EM sensor.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104848"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining representative length in analytical model for artificial ground freezing: A numerical study","authors":"Shun Kikuchi ,&nbsp;Hirotaka Saito ,&nbsp;Masato Oishi ,&nbsp;Kunio Watanabe ,&nbsp;Yusuke Yabuchi","doi":"10.1016/j.coldregions.2026.104842","DOIUrl":"10.1016/j.coldregions.2026.104842","url":null,"abstract":"<div><div>Parameter ambiguity, particularly the representative length <span><math><mi>l</mi></math></span> denoting the overall scale of the frozen wall, frequently impedes the development of analytical models for artificial ground freezing. This study proposes a quantitative methodology for determining <span><math><mi>l</mi></math></span> using numerical simulations. After validating the coupled thermo-hydraulic solver against laboratory experiments, we conducted a parametric study of 12 pipe layouts under varying groundwater velocities. The results showed that the critical flow velocity decreased with the number of pipes owing to the hydraulic dam-up effect. Subsequently, a multiple linear regression model was used to predict <span><math><mi>l</mi></math></span> as a function of the total wall length, pipe density, and their interactions. This analysis revealed that a higher pipe density significantly improved the hydraulic robustness of longer frozen walls. The predictive model achieved a high coefficient of determination of 0.9771. By transforming <span><math><mi>l</mi></math></span> from a vague assumption into a predictable parameter for high-permeability soils, this study bridges numerical simulations and analytical models to enhance engineering design reliability.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104842"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on elevated temperature effect and damage mechanism of frozen soil under impact loading","authors":"Dongdong Ma ,&nbsp;Maoqi Li ,&nbsp;Rongrong Zhang ,&nbsp;Yizhong Tan","doi":"10.1016/j.coldregions.2026.104843","DOIUrl":"10.1016/j.coldregions.2026.104843","url":null,"abstract":"<div><div>A primary methodological constraint in analyzing dynamic damage progression within frozen soil systems arises from experimental limitations in obtaining high-resolution thermal measurements during transient impact loading. To address this challenge, an advanced experimental methodology was developed to synchronously measure the mechanical properties and temperature variation of the measurement points on the surface of frozen soil specimen under impact loading, incorporating a modified split Hopkinson pressure bar (SHPB) coupled with an Infrared Temperature Measurement System (ITMS). In addition, the parameters of the PFC3D model were determined by comparing the simulation and test elevated temperature curves. The elevated temperature field evolution characteristic of frozen soil with various conditions was systematically studied. Moreover, the work-to-heat conversion coefficient (<em>η</em>) of frozen soil was determined by comparing the calculated elevated temperature curves and the simulated results. Finally, the elevated temperature damage mechanism of frozen soil under impact loading was analyzed by revealing the ice-water transformation process. Results demonstrated that the temperature elevation under impact loading showed a gradual and non-uniform progression. The average elevated temperature value of frozen soil increased with the decrease of initial temperature and the increase of strain rate, and its maximum value 1.18 °C was observed under −30 °C initial temperature and 920 s⁻¹ strain rate. The <em>η</em> values of frozen soil ranged from 0.89 to 0.95 spanning a range of subzero temperatures (−10 °C to −30 °C) and strain rates (480 s⁻¹ to 920 s⁻¹). The observed decline in dynamic strength and decreased material brittleness resulting from impact-induced temperature elevation were attributed to three interconnected mechanisms: a progressive reduction in ice crystal content, a concomitant rise in unfrozen water concentration, and the progressive deterioration of interparticle bonding strength throughout thermal loading. The research findings provided significant guidance and served as a valuable reference for practical engineering applications.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"245 ","pages":"Article 104843"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear strength-temperature-moisture content relationship of warm frozen ground for thaw slump stability analysis","authors":"Cedric Rugwizangoga ,&nbsp;Greg Siemens","doi":"10.1016/j.coldregions.2026.104820","DOIUrl":"10.1016/j.coldregions.2026.104820","url":null,"abstract":"<div><div>Permafrost covers nearly 50 % of Canada, co-located with intense climate warming occurring four times the global average. These factors have led to a significant increase in geohazards, including landslides, thawing glaciers, mass wasting, and instability in ice-rich soils. Retrogressive thaw slumps have increased by 60 % in recent decades raising concerns for linear infrastructure, built environment, community, and the environment. Previous research includes both site-specific and remote studies seeking to understand controlling factors of thaw slumps and triggering mechanisms that lead to a range of potential outcomes from significant retrogression, slumping, or self-stabilization. Recently physical modelling in a geotechnical centrifuge has shown that the thaw slump outcome (retrogression through self-stabilization) occurs at temperatures near 0 °C and that ice content plays a significant role. Shear failures observed during physical models give motivation to complete limit equilibrium analysis, however, the shear strength relationship is unknown and difficult to accurately measure in warm frozen ground (between −1 and 0 °C). In this paper, the shear strength-temperature-moisture content relationship of warm frozen ground is reported and used in stability analysis of shear failure thaw slumps. Results showed that shear strength significantly decreases between −1 and 0 °C and then remains constant at positive temperatures. Shear strength is very sensitive to changes in both temperature below zero and moisture content at positive and negative temperatures. Results were implemented in slope stability analyses to illustrate the high sensitivity of factor of safety to temperature and ice/moisture content in thawing fine-grained materials.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"244 ","pages":"Article 104820"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uniaxial compressive behavior of frozen silty clay at extreme low temperature with varying initial water content","authors":"Jiaming Xian ,&nbsp;Wansheng Pei ,&nbsp;Yuanming Lai ,&nbsp;Mingyi Zhang ,&nbsp;Fan Yu ,&nbsp;Yanyan Chen","doi":"10.1016/j.coldregions.2026.104825","DOIUrl":"10.1016/j.coldregions.2026.104825","url":null,"abstract":"<div><div>Current researches on frozen soil mechanics mainly focus on temperature above −30 °C. However, increasing extreme low temperature conditions (e.g., extreme cold weather in cold regions, artificial ground freezing construction, and liquefied natural gas storage) demands a clear understanding of frozen soil mechanics below −30 °C. In this study, uniaxial compression tests were conducted on silty clay samples at varied initial mass water contents (12%, 14%, 16%, 18%, and 20%) and temperatures ranging from −10 °C to −130 °C. The influence of extreme low temperature and initial water content on the mechanical behavior and failure mode were analyzed by combining the macro test and material compositions. The results show that the uniaxial compressive strength (UCS) and elastic modulus increase as temperature decreases for soil with lower initial water content (12% to 16%). In contrast, at higher initial water content (18% to 20%), the UCS rises to a peak at −110 °C and then declines with further cooling. Meanwhile, the shapes of stress-strain curves have three types, including strain softening, strain hardening, and brittleness. All samples exhibit pronounced brittle transition at approximately −110 °C. Two brittleness evaluation methods were employed to quantitatively assess the brittleness level of the soil samples. Moreover, the failure mode also changes with temperature and initial water content, including the localized failure with shear band, the bulge failure, the splitting failure, and the crushing failure. The strength variation at extreme low temperature is attributed to the combined effect of the strength variation of the pore ice and the mineral compositions in soil particles, and the bond effect between ice and soil particles. These findings elucidate the mechanical behavior and the evolution of brittleness in frozen silty clay under extreme low temperature conditions. They can provide a scientific basis for safer geotechnical design and infrastructure resilience in cold environments.</div></div>","PeriodicalId":10522,"journal":{"name":"Cold Regions Science and Technology","volume":"244 ","pages":"Article 104825"},"PeriodicalIF":3.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}