RackBlox: A Software-Defined Rack-Scale Storage System with Network-Storage Co-Design

Software-defined networking (SDN) and software-defined flash (SDF) have been serving as the backbone of modern data centers. They are managed separately to handle I/O requests. At first glance, this is a reasonable design by following the rack-scale hierarchical design principles. However, it suffers from suboptimal end-to-end performance, due to the lack of coordination between SDN and SDF. In this paper, we co-design the SDN and SDF stack by redefining the functions of their control plane and data plane, and splitting up them within a new architecture named RackBlox. RackBlox decouples the storage management functions of flash-based solid-state drives (SSDs), and allow the SDN to track and manage the states of SSDs in a rack. Therefore, we can enable the state sharing between SDN and SDF, and facilitate global storage resource management. RackBlox has three major components: (1) coordinated I/O scheduling, in which it dynamically adjusts the I/O scheduling in the storage stack with the measured and predicted network latency, such that it can coordinate the effort of I/O scheduling across the network and storage stack for achieving predictable end-to-end performance; (2) coordinated garbage collection (GC), in which it will coordinate the GC activities across the SSDs in a rack to minimize their impact on incoming I/O requests; (3) rack-scale wear leveling, in which it enables global wear leveling among SSDs in a rack by periodically swapping data, for achieving improved device lifetime for the entire rack. We implement RackBlox using programmable SSDs and switch. Our experiments demonstrate that RackBlox can reduce the tail latency of I/O requests by up to 5.8x over state-of-the-art rack-scale storage systems.Comment: 14 pages. Published in published in ACM SIGOPS 29th Symposium on Operating Systems Principles (SOSP'23

Pleurorhizoxylon yixingense gen. et sp. nov., a Euphyllophyte Axis with Anatomically Preserved Adventitious Roots from the Late Devonian of South China

Premise of research. Rooting structures were major contributors to Devonian global change, but anatomically preserved plant roots are rare from this period. We report a new type of plant axis from the Upper Devonian strata of South China that contains a protostele, relatively extensive secondary xylem, and adventitious root traces. Methodology. The original specimens were fragmentary coalified axes, most of which were embedded in Epon resin, sectioned transversely and longitudinally, and ground into thin sections. The sections were observed and imaged with a light microscope. A few were observed directly with a scanning electron microscope. Pivotal results. The axis of this new plant, named Pleurorhizoxylon gen. nov., consists of a three-ribbed protostele and thick secondary xylem; the primary xylem is of apparent mesarch maturation, with a single protoxylem lacuna near the end of each rib. The secondary xylem has variable rays composed of parenchyma cells and has scalariform to elliptical bordered pits on both radial and tangential walls of the tracheids. The adventitious root traces are located opposite each primary xylem rib going through the wood; they are accompanied by large rays and cause significant accommodation (knotting) in the wood. Extraxylary portions are poorly preserved, and no cambium or secondary phloem has been found. Conclusions. The new plant has a unique combination of characters and demonstrates the anatomical basis for adventitious root growth present in a Devonian moniliform plant, other than cladoxylopsids, for the first time

Belowground rhizomes in paleosols:The hidden half of an Early Devonian vascular plant

The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant-soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus. The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet-dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant-soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated.National Natural Science Foundation of China [41272018]; Yunnan Key Laboratory for Palaeobiology, Yunnan University [2015DG007-KF04]; Key Laboratory of Economic Stratigraphy and Palaeogeography, Chinese Academy of Sciences (Nanjing Institute of Geology and Palaeontology)SCI(E)[email protected]

CARMA Survey Toward Infrared-bright Nearby Galaxies (STING): Molecular Gas Star Formation Law in NGC4254

This study explores the effects of different assumptions and systematics on the determination of the local, spatially resolved star formation law. Using four star formation rate (SFR) tracers (H\alpha with azimuthally averaged extinction correction, mid-infrared 24 micron, combined H\alpha and mid-infrared 24 micron, and combined far-ultraviolet and mid-infrared 24 micron), several fitting procedures, and different sampling strategies we probe the relation between SFR and molecular gas at various spatial resolutions and surface densities within the central 6.5 kpc in the disk of NGC4254. We find that in the high surface brightness regions of NGC4254 the form of the molecular gas star formation law is robustly determined and approximately linear and independent of the assumed fraction of diffuse emission and the SFR tracer employed. When the low surface brightness regions are included, the slope of the star formation law depends primarily on the assumed fraction of diffuse emission. In such case, results range from linear when the fraction of diffuse emission in the SFR tracer is ~30% or less (or when diffuse emission is removed in both the star formation and the molecular gas tracer), to super-linear when the diffuse fraction is ~50% and above. We find that the tightness of the correlation between gas and star formation varies with the choice of star formation tracer. The 24 micron SFR tracer by itself shows the tightest correlation with the molecular gas surface density, whereas the H\alpha corrected for extinction using an azimuthally-averaged correction shows the highest dispersion. We find that for R<0.5R_25 the local star formation efficiency is constant and similar to that observed in other large spirals, with a molecular gas depletion time ~2 Gyr.Comment: accepted for publication in ApJ, vol 729, March 10 2011 issue; 30 pages; 14 figures; revised version includes referee's comments; results unchange

Comparative Pathogenesis of Three Human and Zoonotic SARS-CoV Strains in Cynomolgus Macaques

The severe acute respiratory syndrome (SARS) epidemic was characterized by increased pathogenicity in the elderly due to an early exacerbated innate host response. SARS-CoV is a zoonotic pathogen that entered the human population through an intermediate host like the palm civet. To prevent future introductions of zoonotic SARS-CoV strains and subsequent transmission into the human population, heterologous disease models are needed to test the efficacy of vaccines and therapeutics against both late human and zoonotic isolates. Here we show that both human and zoonotic SARS-CoV strains can infect cynomolgus macaques and resulted in radiological as well as histopathological changes similar to those seen in mild human cases. Viral replication was higher in animals infected with a late human phase isolate compared to a zoonotic isolate. While there were significant differences in the number of host genes differentially regulated during the host responses between the three SARS-CoV strains, the top pathways and functions were similar and only apparent early during infection with the majority of genes associated with interferon signaling pathways. This study characterizes critical disease models in the evaluation and licensure of therapeutic strategies against SARS-CoV for human use

Stepwise evolution of Paleozoic tracheophytes from South China: contrasting leaf disparity and taxic diversity

During the late Paleozoic, vascular land plants (tracheophytes) diversified into a remarkable variety of morpho- logical types, ranging from tiny, aphyllous, herbaceous forms to giant leafy trees. Leaf shape is a key determinant of both function and structural diversity of plants, but relatively little is known about the tempo and mode of leaf morphological diversification and its correlation with tracheophyte diversity and abiotic changes during this re- markable macroevolutionary event, the greening of the continents. We use the extensive record of Paleozoic tra- cheophytes from South China to explore models of morphological evolution in early land plants. Our findings suggest that tracheophyte leaf disparity and diversity were decoupled, and that they were under different selec- tive regimes. Two key phases in the evolution of South Chinese tracheophyte leaves can be recognized. In the first phase, from Devonian to Mississippian, taxic diversity increased substantially, as did leaf disparity, at the same time as they acquired novel features in their vascular systems, reproductive organs, and overall architecture. The second phase, through the Carboniferous–Permian transition, saw recovery of wetland communities in South China, associated with a further expansion of morphologies of simple leaves and an offset shift in morphospace occupation by compound leaves. Comparison with Euramerica suggests that the floras from South China were unique in several ways. The Late Devonian radiation of sphenophyllaleans contributed signif- icantly to the expansion of leaf morphospace, such that the evolution of large laminate leaves in this group oc- curred much earlier than those in Euramerica. The Pennsylvanian decrease in taxic richness had little effect on the disparity of compound leaves. Finally, the distribution in morphospace of the Permian pecopterids, gigantopterids, and equisetaleans occurred at the periphery of Carboniferous leaf morphospace

The Impact of Green Innovation on a Firm’s Value from the Perspective of Enterprise Life Cycles

Many studies focus on the impact of green innovation on enterprises, but few studies pay attention to the difference made by the impact of green innovation at the different stages of a firm’s life cycle. This study used Chinese A-share listed companies as a sample to conduct research and found that green innovation has a positive effect on a firm’s value. However, compared with firms at a mature stage of their life cycle, the impact of green innovation on firm value is more significant in firms at the stages of growth and decline. Further research shows that green innovation can increase the value of firms at the growth stage by improving their sustainable development capability and reducing debt financing costs. However, for firms at the decline stage of their life cycle, green innovation can only increase firm value by reducing debt financing costs. In addition, the nature of property rights and the level of corporate governance will have a moderating effect on the relationship between green innovation and firm value. This research will not only enrich the previous literature but also guide the allocation of resources for firms at different stages of their life cycle to carry out green innovation