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- Dong, Jianbo, et al.
(författare)
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Venice: Exploring Server Architectures for Effective Resource Sharing
- 2016
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Ingår i: Proceedings - International Symposium on High-Performance Computer Architecture. - 1530-0897. - 9781467392112 ; 2016-April, s. 507-518
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Konferensbidrag (refereegranskat)abstract
- Consolidated server racks are quickly becoming the backbone of IT infrastructure for science, engineering, and business, alike. These servers are still largely built and organized as when they were distributed, individual entities. Given that many fields increasingly rely on analytics of huge datasets, it makes sense to support flexible resource utilization across servers to improve cost-effectiveness and performance. We introduce Venice, a family of data-center server architectures that builds a strong communication substrate as a first-class resource for server chips. Venice provides a diverse set of resource-joining mechanisms that enables user programs to efficiently leverage non-local resources.To better understand the implications of design decisionsabout system support for resource sharing we have constructed a hardware prototype that allows us to more accurately measure end-to-end performance of at-scale applications and to explore tradeoffs among performance, power, and resource-sharing transparency. We present results from our initial studies analyzing these tradeoffs when sharing memory, accelerators, or NICs. We find that it is particularly important to reduce or hide latency, that data-sharing access patterns should match the features of the communication channels employed, and that inter-channel collaboration can be exploited for better performance.
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- Dong, Xi-ping, et al.
(författare)
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Developmental biology of the early Cambrian cnidarian Olivooides.
- 2016
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Ingår i: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 59:3, s. 387-407
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Tidskriftsartikel (refereegranskat)abstract
- Fossilized embryos afford direct insight into the pattern of development in extinct organisms, providing unique tests of hypotheses of developmental evolution based in comparative embryology. However, these fossils can only be effective in this role if their embryology and phylogenetic affinities are well constrained. We elucidate and interpret the development of Olivooides from embryonic and adult stages and use these data to discriminate among competing interpretations of their anatomy and affinity. The embryology of Olivooides is principally characterized by the development of an ornamented periderm that initially forms externally and is subsequently formed internally, released at the aperture, facilitating the direct development of the embryo into an adult theca. Internal anatomy is known only from embryonic stages, revealing two internal tissue layers, the innermost of which is developed into three transversally arranged walls that partly divide the lumen into an abapertural region, interpreted as the gut of a polyp, and an adapertural region that includes structures that resemble the peridermal teeth of coronate scyphozoans. The anatomy and pattern of development exhibited by Olivooides appears common to the other known genus of olivooid, Quadrapyrgites, which differs in its tetraradial, as opposed to pentaradial symmetry. We reject previous interpretations of the olivooids as cycloneuralians, principally on the grounds that they lack a through gut and introvert, in embryo and adult. Instead we consider the affinities of the olivooids among medusozoan cnidarians; our phylogenetic analysis supports their classification as totalgroup Coronata, within crown-Scyphozoa. Olivooides and Quadrapyrgites evidence a broader range of life history strategies and bodyplan symmetry than is otherwise commonly represented in extant Scyphozoa specifically, and Cnidaria more generally.
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- Dong, Xi-ping, et al.
(författare)
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Embryos, polyps and medusae of the early Cambrian scyphozoan Olivooides.
- 2013
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Ingår i: Proceedings of the Royal Society Biological Sciences Series B. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 280:2130071, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The Early Cambrian organism Olivooides is known from both embryonic and post-embryonic stages and, consequently, it has the potential to yield vital insights into developmental evolution at the time that animal body plans were established. However, this potential can only be realized if the phylogenetic relationships of Olivooides can be constrained. The affinities of Olivooides have proved controversial because of the lack of knowledge of the internal anatomy and the limited range of developmental stages known. Here, we describe rare embryonic specimens in which internal anatomical features are preserved. We also present a fuller sequence of fossilized developmental stages of Olivooides, including associated specimens that we interpret as budding ephyrae ( juvenile medusae), all of which display a clear pentaradial symmetry. Within the framework of a cnidarian interpretation, the new data serve to pinpoint the phylogenetic position of Olivooides to the scyphozoan stem group. Hypotheses about scalidophoran or echinoderm affinities of Olivooides can be rejected.
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- Jiang, Tao, et al.
(författare)
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Adapting Memory Hierarchies for Emerging Datacenter Interconnects
- 2015
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Ingår i: Journal of Computer Science and Technology. - : Springer Science and Business Media LLC. - 1860-4749 .- 1000-9000. ; 30:1, s. 97-109
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Tidskriftsartikel (refereegranskat)abstract
- Efficient resource utilization requires that emerging datacenter interconnects support both high performance communication and efficient remote resource sharing. These goals require that the network be more tightly coupled with the CPU chips. Designing a new interconnection technology thus requires considering not only the interconnection itself, but also the design of the processors that will rely on it. In this paper, we study memory hierarchy implications for the design of high-speed datacenter interconnects particularly as they affect remote memory access and we use PCIe as the vehicle for our investigations. To that end, we build three complementary platforms: a PCIe-interconnected prototype server with which we measure and analyze current bottlenecks; a software simulator that lets us model microarchitectural and cache hierarchy changes; and an FPGA prototype system with a streamlined switchless customized protocol Thunder with which we study hardware optimizations outside the processor. We highlight several architectural modifications to better support remote memory access and communication, and quantify their impact and limitations.
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- Liu, Teng, et al.
(författare)
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Soft- tissue anatomy of an orsten- type phosphatocopid crustacean from the cambrian furongian of China revealed by synchrotron radiation x-ray tomographic microscopy
- 2019
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Ingår i: Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen. - : Schweizerbart. - 0077-7749. ; 294:3, s. 263-274
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Tidskriftsartikel (refereegranskat)abstract
- Fossils of Orsten- type preservation represented by Skara and Phosphatocopida have been reported from the Cambrian Furongian of Western Hunan, China. Their taxonomy and external morphology are well known, but their internal soft- tissue anatomy has not been revealed yet. With the application of synchrotron radiation X-ray tomographic microscopy, here we describe the internal soft- tissue anatomy of an Orsten- type preserved phosphatocopid crustacean assigned to Hesslandona angustata. The internal organs and tissues of this specimen were collapsed after death to form a visceral mass situated within the labrum and underneath the sternal cuticle. The visceral mass contains the digestive system, including digestive tract and possible digestive glands. The digestive tract starts from the mouth, followed by oesophagus (foregut) and midgut, whereas the hind gut and anus are unknown due to incomplete preservation. Two bilaterally symmetric knob- like structures beside the midgut may be digestive glands (midgut diverticula). The visceral mass also contains other structures that may be related to nerve tissues and/or muscles, but identification as specific organs or tissues is uncertain.
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- Wang, Dong, 1987-
(författare)
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New Reactions with Allyl- and Allenylboron Reagents : Transition-Metal-Catalyzed and Transition-Metal-Free Carbon-Carbon Bond Formation Processes
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organoboron compounds have been widely used in carbon-carbon bond formation reactions in organic synthesis and catalysis. This thesis is focused on cross-coupling reactions of allyl-, allenylboronic acids and their ester derivatives via transition metal catalysis or transition-metal-free processes.The first part of the thesis describes Cu-catalyzed C(sp3)-C(sp3) formation reactions involving allylboronic acids and α-diazoketones. This coupling process shows high γ-regioselectivity, resulting in branched allylic products. When stereodefined cyclic allylboronic acids were employed as the substrate, the relative facial configuration was retained in the reaction product.The second part involves Pd-catalyzed cross-coupling of allylboronic acid and α-diazoketones. The reaction proceeds with high α-regioselectivity, affording linear allylic products. Accordingly, the palladium- and copper-catalyzed cross-coupling of allylboronic acid and α-diazoketones occurs with opposite regioselectivity.The third part concerns a new transition-metal-free carbon-carbon bond formation between allenylboronic acids and in situ generated diazo compounds. The diazo compounds are generated from tosylhydrazones in the presence of base. The reaction is suitable for synthesis of densely substituted conjugated dienes with high Z-selectivity.In the final part, the allylation of quinones with allylboronates is presented. The reaction was performed without any catalyst or additive. Various quinones can be employed as substrates, including unsubstituted, monosubstituted benzoquinones and naphthoquinones.
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8. |
- Zhang, Liuhang, et al.
(författare)
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P-Socket: Optimizing a communication library for a PCIe-based intra-rack interconnect
- 2016
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Ingår i: ACM International Conference on Computing Frontiers, CF 2016; Como; Italy; 16 May 2016 through 18 May 2016. - New York, NY, USA : ACM. - 9781450341288 ; , s. 145-153
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Konferensbidrag (refereegranskat)abstract
- Data centers require efficient, low-cost, exible interconnects to manage the rapidly growing internal traffic generated by an increasingly diverse set of applications. To meet these re-quirements, data center networks are increasingly employing alternatives such as RapidIO, Freedom, and PCIe, which re-quire fewer physical devices and/or have simpler protocols than more traditional interconnects. These networks offer raw high performance communication capabilities, but sim-ply using them for conventional TCP/IP-based communica-tion fails to realize the potential performance of the physical network. Here we analyze causes for this performance loss for the TCP/IP protocol over one such fabric, PCIe, and we explore a hardware/software solution that mitigates over-heads and exploits PCIe's advanced features. The result is P-Socket, an efficient library that enables legacy socket applications to run without modification. Our experiments show that P-Socket achieves an end-To-end latency of 1.2s and effiective bandwidth of up to 2.87GB/s (out of a theo-retical peak of 3.05GB/s).
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