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  1. Abstract

    Seismic tomography models indicate highly variable Earth structure beneath Antarctica with anomalously low shallow mantle viscosities below West Antarctica. An improved projection of the contribution of the Antarctic Ice Sheet to sea‐level change requires consideration of this complexity to precisely account for water expelled into the ocean from uplifting marine sectors. Here we build a high‐resolution 3‐D viscoelastic structure model based on recent inferences of seismic velocity heterogeneity below the continent. The model serves as input to a global‐scale sea‐level model that we use to investigate the influence of solid Earth deformation in Antarctica on future global mean sea‐level (GMSL) rise. Our calculations are based on a suite of ice mass projections generated with a range of climate forcings and suggest that water expulsion from the rebounding marine basins contributes 4%–16% and 7%–14% to the projected GMSL change at 2100 and 2500, respectively.

     
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  2. Host-managed shingled magnetic recording drives (HMSMR) give a capacity advantage to harness the explosive growth of data. Applications where data is sequentially written and randomly read, such as key-value stores based on Log-Structured Merge Trees (LSM-trees), make the HMSMR an ideal solution due to its capacity, predictable performance, and economical cost. However, building an LSMtree based KV store on HM-SMR drives presents severe challenges in maintaining the performance and space efficiency due to the redundant cleaning processes for applications and storage devices (i.e., compaction and garbage collections). To eliminate the overhead of on-disk garbage collections (GC) and improve compaction efficiency, this paper presents GearDB, a GC-free KV store tailored for HMSMR drives. GearDB proposes three new techniques: a new on-disk data layout, compaction windows, and a novel gear compaction algorithm. We implement and evaluate GearDB with LevelDB on a real HM-SMR drive. Our extensive experiments have shown that GearDB achieves both good performance and space efficiency, i.e., on average 1:71 faster than LevelDB in random write with a space efficiency of 89.9%. 
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  3. Free, publicly-accessible full text available June 1, 2025
  4. Key-value (KV) stores play an increasingly critical role in supporting diverse large-scale applications in modern data centers hosting terabytes of KV items which even might reside on a single server due to virtualization purpose. The combination of ever growing volume of KV items and storage/application consolidation is driving a trend of high storage density for KV stores. Shingled Magnetic Recording (SMR) represents a promising technology for increasing disk capacity, but it comes at a cost of poor random write performance and severe I/O amplification. Applications/software working with SMR devices need to be designed and optimized in an SMR-friendly manner. In this work, we present SEALDB, a Log-Structured Merge tree (LSM-tree) based key-value store that is specifically op- timized for and works well with SMR drives via adequately addressing the poor random writes and severe I/O amplification issues. First, for LSM-trees, SEALDB concatenates SSTables of each compaction, and groups them into sets. Taking sets as the basic unit for compactions, SEALDB improves compaction efficiency by mitigating random I/Os. Second, SEALDB creates varying size bands on HM-SMR drives, named dynamic bands. Dynamic bands not only accommodate the storage of sets, but also eliminate the auxiliary write amplification from SMR drives. We demonstrate the advantages of SEALDB via extensive experiments in various workloads. Overall, SEALDB delivers impressive performance improvement. Compared with LevelDB, SEALDB is 3.42× faster on random load due to improved compaction efficiency and eliminated auxiliary write amplification on SMR drives. 
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  5. NAND flash-based Solid State Devices (SSDs) offer the desirable features of high performance, energy efficiency, and fast growing capacity. Thus, the use of SSDs is increasing in distributed storage systems. A key obstacle in this context is that the natural unbalance in distributed I/O workloads can result in wear imbalance across the SSDs in a distributed setting. This, in turn can have significant impact on the reliability, performance, and lifetime of the storage deployment. Extant load balancers for storage systems do not consider SSD wear imbalance when placing data, as the main design goal of such balancers is to extract higher performance. Consequently, data migration is the only common technique for tackling wear imbalance, where existing data is moved from highly loaded servers to the least loaded ones. In this paper, we explore an innovative holistic approach, Chameleon, that employs data redundancy techniques such as replication and erasure-coding, coupled with endurance-aware write offloading, to mitigate wear level imbalance in distributed SSD-based storage. Chameleon aims to balance the wear among different flash servers while meeting desirable objectives of: extending life of flash servers; improving I/O performance; and avoiding bottlenecks. Evaluation with a 50 node SSD cluster shows that Chameleon reduces the wear distribution deviation by 81% while improving the write performance by up to 33%. 
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  6. A<sc>bstract</sc>

    The production yields of the Σ(1385)±and Ξ(1530)0resonances are measured in pp collisions at$$ \sqrt{s} $$s= 13 TeV with ALICE. The measurements are performed as a function of the charged-particle multiplicity ⟨dNch/dη⟩, which is related to the energy density produced in the collision. The results include transverse momentum (pT) distributions,pT-integrated yields, mean transverse momenta of Σ(1385)±and Ξ(1530)0, as well as ratios of thepT-integrated resonance yields relative to yields of other hadron species. The Σ(1385)±±and Ξ(1530)0±yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared with predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the Σ(1385)±and Ξ(1530)0production in pp collisions at$$ \sqrt{s} $$s= 13 TeV.

     
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    Free, publicly-accessible full text available May 1, 2025
  7. A<sc>bstract</sc>

    Measurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision$$ \sqrt{s_{\textrm{NN}}} $$sNN= 5.02 TeV and the corresponding nuclear modification factor$$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$RpPbchjetare presented, using data collected with the ALICE detector at the LHC. Jets are reconstructed in the central rapidity region |ηjet|<0.5 from charged particles using the anti-kTalgorithm with resolution parametersR= 0.2, 0.3, and 0.4. ThepT-differential inclusive production cross section of charged-particle jets, as well as the corresponding cross section ratios, are reported for pp and p-Pb collisions in the transverse momentum range 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$pT,jetch<140 GeV/cand 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$pT,jetch<160 GeV/c, respectively, together with the nuclear modification factor$$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$RpPbchjetin the range 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$pT,jetch<140 GeV/c. The analysis extends thepTrange of the previously-reported charged-particle jet measurements by the ALICE Collaboration. The nuclear modification factor is found to be consistent with one and independent of the jet resolution parameter with the improved precision of this study, indicating that the possible influence of cold nuclear matter effects on the production cross section of charged-particle jets in p-Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$sNN= 5.02 TeV is smaller than the current precision. The obtained results are in agreement with other minimum bias jet measurements available for RHIC and LHC energies, and are well reproduced by the NLO perturbative QCD Powhegcalculations with parton shower provided by Pythia8 as well as by Jetscapesimulations.

     
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    Free, publicly-accessible full text available May 1, 2025
  8. K+Kpairs may be produced in photonuclear collisions, either from the decays of photoproducedϕ(1020)mesons or directly as nonresonantK+Kpairs. Measurements ofK+Kphotoproduction probe the couplings between theϕ(1020)and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction ofK+Kpairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of directK+Kproduction. There is significantK+Kproduction at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range1.1<MKK<1.4GeV/c2above theϕ(1020)resonance, for rapidity|yKK|<0.8andpT,KK<0.1GeV/c, the measured coherent photoproduction cross section isdσ/dy=3.37±0.61(stat)±0.15(syst)mb. The center-of-mass energy per nucleon of the photon-nucleus (Pb) systemWγPb,nranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected forϕ(1020)photoproduction alone. The mass spectrum is fit to a cocktail consisting ofϕ(1020)decays, directK+Kphotoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for directK+Kphotoproduction are presented.

    <supplementary-material><permissions><copyright-statement>© 2024 CERN, for the ALICE Collaboration</copyright-statement><copyright-year>2024</copyright-year><copyright-holder>CERN</copyright-holder></permissions></supplementary-material></sec> </div> <a href='#' class='show open-abstract' style='margin-left:10px;'>more »</a> <a href='#' class='hide close-abstract' style='margin-left:10px;'>« less</a> <div class="actions" style="padding-left:10px;"> <span class="reader-count"> Free, publicly-accessible full text available May 1, 2025</span> </div> </div><div class="clearfix"></div> </div> </li> <li> <div class="article item document" itemscope itemtype="http://schema.org/TechArticle"> <div class="item-info"> <div class="title"> <a href="https://par.nsf.gov/biblio/10514233-light-flavor-particle-production-high-multiplicity-pp-collisions-sqrt-textrm-tev-function-transverse-spherocity" itemprop="url"> <span class='span-link' itemprop="name">Light-flavor particle production in high-multiplicity pp collisions at $$ \sqrt{\textrm{s}} $$ = 13 TeV as a function of transverse spherocity</span> </a> </div> <div> <strong> <a class="misc external-link" href="https://doi.org/10.1007/JHEP05(2024)184" target="_blank" title="Link to document DOI">https://doi.org/10.1007/JHEP05(2024)184  <span class="fas fa-external-link-alt"></span></a> </strong> </div> <div class="metadata"> <span class="authors"> <span class="author" itemprop="author">Acharya, S</span> <span class="sep">; </span><span class="author" itemprop="author">Adamová, D</span> <span class="sep">; </span><span class="author" itemprop="author">Aglieri_Rinella, G</span> <span class="sep">; </span><span class="author" itemprop="author">Agnello, M</span> <span class="sep">; </span><span class="author" itemprop="author">Agrawal, N</span> <span class="sep">; </span><span class="author" itemprop="author">Ahammed, Z</span> <span class="sep">; </span><span class="author" itemprop="author">Ahmad, S</span> <span class="sep">; </span><span class="author" itemprop="author">Ahn, S U</span> <span class="sep">; </span><span class="author" itemprop="author">Ahuja, I</span> <span class="sep">; </span><span class="author" itemprop="author">Akindinov, A</span> <span class="sep">; </span><span class="author">et al</span></span> <span class="year">( <time itemprop="datePublished" datetime="2024-05-01">May 2024</time> , Journal of High Energy Physics) </span> </div> <div style="cursor: pointer;-webkit-line-clamp: 5;" class="abstract" itemprop="description"> <title>A<sc>bstract</sc>

    Results on the transverse spherocity dependence of light-flavor particle production (π, K, p,ϕ, K*0,$$ {\textrm{K}}_{\textrm{S}}^0 $$KS0, Λ, Ξ) at midrapidity in high-multiplicity pp collisions at$$ \sqrt{s} $$s= 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator$$ \left({S}_{\textrm{O}}^{p_{\textrm{T}}=1}\right) $$SOpT=1categorizes events by their azimuthal topology. Utilizing narrow selections on$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$SOpT=1, it is possible to contrast particle production in collisions dominated by many soft initial interactions with that observed in collisions dominated by one or more hard scatterings. Results are reported for two multiplicity estimators covering different pseudorapidity regions. The$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$SOpT=1estimator is found to effectively constrain the hardness of the events when the midrapidity (|η| < 0.8) estimator is used.

    The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced.

    The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$SOpT=1.

     
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    Free, publicly-accessible full text available May 1, 2025