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1. BBB: Simplifying Persistent Programming using Battery-Backed Buffers

   https://doi.org/10.1109/HPCA51647.2021.00019  

   Alshboul, Mohammad; Ramrakhyani, Prakash; Wang, William; Tuck, James; Solihin, Yan (February 2021, 2021 IEEE International Symposium on High-Performance Computer Architecture (HPCA))

   null (Ed.)

   Non-volatile memory (NVM) is poised to augment or replace DRAM as main memory. With the right abstraction and support, non-volatile main memory (NVMM) can provide an alternative to the storage system to host long-lasting persistent data. However, keeping persistent data in memory requires programs to be written such that data is crash consistent (i.e. it can be recovered after failure). Critical to supporting crash recovery is the guarantee of ordering of when stores become durable with respect to program order. Strict persistency, which requires persist order to coincide with program order of stores, is simple and intuitive but generally thought to be too slow. More relaxed persistency models are available but demand higher programming complexity, e.g. they require the programmer to insert persist barriers correctly in their program. We identify the source of strict persistency inefficiency as the gap between the point of visibility (PoV) which is the cache, and the point of persistency (PoP) which is the memory. In this paper, we propose a new approach to close the PoV/PoP gap which we refer to as Battery-Backed Buffer (BBB). The key idea of BBB is to provide a battery-backed persist buffer (bbPB) in each core next to the L1 data cache (L1D). A store value is allocated in the bbPB as it is written to cache, becoming part of the persistence domain. If a crash occurs, battery ensures bbPB can be fully drained to NVMM. BBB simplifies persistent programming as the programmer does not need to insert persist barriers or flushes. Furthermore, our BBB design achieves nearly identical results to eADR in terms of performance and number of NVMM writes, while requiring two orders of magnitude smaller energy and time to drain. 

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2. Acoustic and flow measurements of porous plate designs for aerodynamic noise mitigation

   Kershner, John R (August 2024, Lehigh University)

   An experimental study investigates parametrically the effects of porosity on the acoustic and aerodynamic fields about lifting- and non-lifting surfaces at two separate aeroacoustic facilities using microphone arrays and hot-wire anemometry. A single dimensionless porosity parameter characterizes the flow noise generated by a turbulent boundary layer and informs the design of the porous edge test specimens, including perforated flat plates and flat-plate extensions with a blunt or sharp trailing edge. The strong tonal peak due to vortex shedding from blunt trailing-edges diminishes in magnitude as the porosity parameter increases, and high-porosity plates eliminate this tone from the acoustic spectra. Single-microphone measurements indicate further that the porous plates examined can reduce low-frequency noise and increase high-frequency excess noise levels by up to 10 dB. DAMAS beamforming of the porous plates with sharpened edges reveal similar results on the acoustic spectra and identify that the principal effect of edge porosity on the acoustic source regions is a reduction in low-frequency noise and an increase in high-frequency noise across the entire plate. Noise generated by porous edges in the low-frequency range by the trailing- and leading-edge regions can be reduced by up to 20 dB, and porous edges increase high-frequency noise by up to 20 dB. Plates with the same dimensionless porosity perform similarly, where plates with circular holes perform slightly better (2 dB) than their counterparts with square holes at reducing low-frequency noise the most and increasing high-frequency noise the least in wind tunnel testing. Hot-wire anemometry of the flow field about blunt porous trailing edges reveals a downward shift of the bluntness-induced vortex-shedding peak in the spectra of turbulent velocity fluctuations, which are not seen in the acoustic spectra. In addition, flow field measurements for both the blunt-edged and sharp-edge plates indicate significant increases in turbulence intensity at the plate surface which are believed to be caused by the presence of holes and related to the increase in noise seen at high frequencies. The wing of a remote-controlled glider is modified with porous plates near the trailing edge to demonstrate reductions in surface pressure level fluctuations on a flying vehicle at the owl scale. Measurements of these fluctuations on the wing and fuselage indicate the capacity of porous plates to modestly reduce surface pressure levels in select frequency ranges and settings of aerial vehicles. 

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3. Lithics in the Maya Region: Exploring Gendered Trends in Research in the Last Decade

   https://doi.org/10.1017/laq.2023.64  

   Horowitz, Rachel A; Brouwer_Burg, Marieka (April 2024, Latin American Antiquity)

   Abstract Even though lithics in the Maya region have traditionally been relegated to appendices and tool-type lists, much has been done to move beyond this descriptive approach in the last decade. In this article we highlight general themes of lithic studies in the Maya region since 2011, including economic production and exchange, the role of lithics in ritual practice, and the use of previously understudied raw materials and lithic forms, such as ground stone. Employing a temporal scope that encompasses the Maya and their preceramic predecessors, we explore gendered patterns of research within lithic studies from a feminist perspective and discuss the impacts that gender disparities have on academic thought. 

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4. The First Million Years of Technology: The Lomekwian and the Early Oldowan

   https://doi.org/10.1146/annurev-anthro-071923-112250  

   Plummer, Thomas W; Harmand, Sonia; Finestone, Emma M; Wilson, Evan P (July 2025, Annual Review of Anthropology)

   During the course of human evolution, lithic technology became a critical element of hominin foraging ecology and a contributor to feedback loops selecting for increasingly sophisticated tool use, cognition, and language. Here we review the first million years of technology, from 3.3 million years ago (Ma) to 2.3 Ma. This time interval includes the two oldest archaeological industries (the Lomekwian and the early Oldowan) known exclusively from Africa, which collectively overlap with four genera of hominins (human relatives and ancestors). These Early Stone Age (ESA) industries focused on the production and use of sharp edges for cutting, as well as the use of larger, sometimes unworked stones for pounding. We review our current understanding of these technologies, where they were found, how they were made, what they were used for, and the hominins that could have produced them, and consider them in the context of nonhuman primate archaeology. 

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5. The Effect of Elastomer Content and Annealing on the Physical Properties of Upcycled Polyethylene Terephthalate-Maleated Styrene Ethylene Butylene Styrene Blends for Additive Manufacturing

   https://doi.org/10.3390/ma17246272  

   Bermudez, Diego; Moreno, Stephanie; Roberson, David A (December 2024, Materials)

   Santagata, Antonio (Ed.)

   In the work presented here, we explore the upcycling of polyethylene terephthalate (PET) that was derived from water bottles. The material was granulated and extruded into a filament compatible with fused filament fabrication (FFF) additive manufacturing platforms. Three iterations of PET combined with a thermoplastic elastomer, styrene ethylene butylene styrene with a maleic anhydride graft (SEBS-g-MA), were made with 5, 10, and 20% by mass elastomer content. The elastomer and specific mass percentages were chosen based on prior successes involving acrylonitrile butadiene styrene (ABS), in which the maleic anhydride graft enabled compatibility between different materials. The rheological properties of PET and the PET/SEBS blends were characterized by the melt flow index and dynamic mechanical analysis. The addition of SEBS-g-MA did not have a significant impact on mechanical properties, as determined by tensile and impact testing, where all test specimens were manufactured by FFF. Delamination of the tensile specimens convoluted the ability to discern differences in the mechanical properties, particularly % elongation. Annealing of the specimens enabled the observation of the effect of elastomer content on the mechanical properties, particularly in the case of impact testing, where the impact strength increased with the increase in SEBS content. However, annealing led to shrinkage of the specimens, detracting from the realized benefits of the thermal process. Scanning electron microscopy of spent tensile specimens revealed that, in the non-annealed condition, SEBS formed nodules that would detach from the PET matrix during the tensile test, indicating that a robust bond was not present. The addition of SEBS-g-MA did allow for shape memory property characterization, where deformation of tensile specimens occurred at room temperature. Specimens from the 20% by mass elastomer content sample group exhibited a shape fixation ratio on the order of 99% and a shape recovery ratio on the order of 80%. This work demonstrates a potential waste reduction strategy to tackle the problem of polymer waste by upcycling discarded plastic into a feedstock material for additive manufacturing with shape memory properties. 

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