4,998 research outputs found
LogBase: A Scalable Log-structured Database System in the Cloud
Numerous applications such as financial transactions (e.g., stock trading)
are write-heavy in nature. The shift from reads to writes in web applications
has also been accelerating in recent years. Write-ahead-logging is a common
approach for providing recovery capability while improving performance in most
storage systems. However, the separation of log and application data incurs
write overheads observed in write-heavy environments and hence adversely
affects the write throughput and recovery time in the system. In this paper, we
introduce LogBase - a scalable log-structured database system that adopts
log-only storage for removing the write bottleneck and supporting fast system
recovery. LogBase is designed to be dynamically deployed on commodity clusters
to take advantage of elastic scaling property of cloud environments. LogBase
provides in-memory multiversion indexes for supporting efficient access to data
maintained in the log. LogBase also supports transactions that bundle read and
write operations spanning across multiple records. We implemented the proposed
system and compared it with HBase and a disk-based log-structured
record-oriented system modeled after RAMCloud. The experimental results show
that LogBase is able to provide sustained write throughput, efficient data
access out of the cache, and effective system recovery.Comment: VLDB201
A nonlocal sinusoidal shear deformation beam theory with application to bending, buckling, and vibration of nanobeams
This paper presents a nonlocal sinusoidal shear deformation beam theory for the bending, buckling, and vibration of nanobeams. The present model is capable of capturing both small scale effect and transverse shear deformation effects of nanobeams, and does not require shear correction factors. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion as well as the boundary conditions of the beam are derived using Hamilton’s principle. Analytical solutions for the deflection, buckling load, and natural frequency are presented for a simply supported beam, and the obtained results are compared with those predicted by the nonlocal Timoshenko beam theory. The comparison firmly establishes that the present beam theory can accurately predict the bending, buckling, and vibration responses of short nanobeams where the small scale and transverse shear deformation effects are significant
High fat diet deviates PtC-specific B1 B cell phagocytosis in obese mice
Phagocytosis had been attributed predominantly to "professional" phagocytes such as macrophages, which play critical roles in adipose tissue inflammation. However, recently, macrophage-like phagocytic activity has been reported in B1 B lymphocytes. Intrigued by the long-established correlation between high fat diet (HFD)-induced obesity and immune dysfunction, we investigated how HFD affects B1 B cell phagocytosis. A significant number of B1 B cells recognize phosphatidylcholine (PtC), a common phospholipid component of cell membrane. We report here that unlike macrophages, B1 B cells have a unique PtC-specific phagocytic function. In the presence of both PtC-coated and non-PtC control fluorescent nano-particles, B1 B cells from healthy lean mice selectively engulfed PtC-coated beads, whereas B1 B cells from HFD-fed obese mice non-discriminately phagocytosed both PtC-coated and control beads. Morphologically, B1 B cells from obese mice resembled macrophages, displaying enlarged cytosol and engulfed more beads. Our study suggests for the first time that HFD can affect B1 B cell phagocytosis, substantiating the link of HFD-induced obesity and immune deviation.R21 AR063387 - NIAMS NIH HHS; R25 CA153955 - NCI NIH HHS; UL1 TR000157 - NCATS NIH HH
A zoomable shopping browser using a graphic-treemap
Effective and efficient navigation and representation of the entire structure of the product catalogue is one of the important factors for on-line market. This paper proposes an application using Treemaps visualization to enhance the functionality of online product category. We aim to develop high-quality catalog interfaces in terms of readability, understandability and comprehension by integrating graphics into Treemaps. We applied two types of Treemaps: 1) Slice-and-Dice Treemap, 2) Squarified Treemap, into the on-line catalogue to address the small windowproblem allowing buyers to overview and navigate large product categories dynamically. We also use a history bar that locates on the top of each category and sub-category to provide a 2.5-dimensional view of contextual information. © 2009 IEEE
The System: The Administration Presentation
Research and Capstone projects
Building on the 2017 fall semester and insights from the Fall 2017 trip to Los Angeles, student working groups will predict the future of a system or related issue for an audience of their peers, offering reflections on navigating that future. These projects might take the form of posters, video installations, original speculative fiction, or mixed media that will be incorporated into the atmosphere of a campus party, both to maximize the student audience, and to celebrate our determination for an exciting future.https://scholarship.richmond.edu/ssir-presentations-2018/1002/thumbnail.jp
Performance of periodic EOM-CCSD for band gaps of inorganic semiconductors and insulators
We calculate the band gaps of 12 inorganic semiconductors and insulators
composed of atoms from the first three rows of the periodic table using
periodic equation-of-motion coupled-cluster theory with single and double
excitations (EOM-CCSD). Our calculations are performed with atom-centered
triple-zeta basis sets and up to 64 -points in the Brillouin zone. We
analyze the convergence behavior with respect to number of orbitals and number
of -points sampled, using composite corrections and extrapolations to
produce our final values. When accounting for electron-phonon corrections to
experimental band gaps, we find that EOM-CCSD has a mean signed error of
eV and a mean absolute error of eV; the largest outliers are C
(error of eV), BP ( eV), and LiH ( eV). Surprisingly, we
find that the more affordable partitioned EOM-MP2 theory performs as well as
EOM-CCSD.Comment: 6 pages, 5 figures, 1 tabl
Bottom-up synthesis of nitrogen-doped nanocarbons by a combination of metal catalysis and a solution plasma process
We aimed to develop the bottom-up synthesis of nanocarbons with specific functions from molecules without any leaving group, halogen atom and boronic acid, by employing a metal catalyst under solution plasma irradiation. Pyridine was used as a source of carbon. In the presence of a Pd catalyst, the plasma treatment enabled the synthesis of N-doped carbons with a pyridinic configuration, which worked as an active catalytic site for the oxygen reduction reaction
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