2,299 research outputs found
LASR-Guided Stellar Photometric Variability Subtraction: The Linear Algorithm For Significance Reduction
We develop a technique for removing stellar variability in the light curves
of -Scuti and similar stars. Our technique, which we name the Linear
Algorithm for Significance Reduction (LASR), subtracts oscillations from a time
series by minimizing their statistical significance in frequency space. We
demonstrate that LASR can subtract variable signals of near-arbitrary
complexity and can robustly handle close frequency pairs and overtone
frequencies. We demonstrate that our algorithm performs an equivalent fit as
prewhitening to the straightforward variable signal of KIC 9700322. We also
show that LASR provides a better fit to seismic activity than prewhitening in
the case of the complex -Scuti KOI-976.Comment: 9 pages, 5 figures, accepted for publication in Astronomy &
Astrophysics. Pseudocode and github link to code included in manuscrip
Inter-temporal changes in ethnic urban earnings disparities in China
Chapter from: 'Rising Inequality in China: Challenge to a Harmonious Society', edited by Shi Li, Hiroshi Sato and Terry Sicular
Renormalization of Boundary Fermions and World-Volume Potentials on D-branes
We consider a sigma model formulation of open string theory with boundary
fermions carrying Chan-Paton charges at the string ends. This formalism is
particularly suitable for studying world-volume potentials on D-branes. We
perform explicit two-loop sigma model computations of the potential T-dual to
the non-abelian Born-Infeld action. We also discuss the world-volume couplings
of NS fluxes which are responsible for Myers' dielectric effect.Comment: 17 pages, 8 figure
Automatic partitioning of database applications
Database-backed applications are nearly ubiquitous in our daily lives. Applications that make many small accesses to the database create two challenges for developers: increased latency and wasted resources from numerous network round trips. A well-known technique to improve transactional database application performance is to convert part of the application into stored procedures that are executed on the database server. Unfortunately, this conversion is often difficult. In this paper we describe Pyxis, a system that takes database-backed applications and automatically partitions their code into two pieces, one of which is executed on the application server and the other on the database server. Pyxis profiles the application and server loads, statically analyzes the code's dependencies, and produces a partitioning that minimizes the number of control transfers as well as the amount of data sent during each transfer. Our experiments using TPC-C and TPC-W show that Pyxis is able to generate partitions with up to 3x reduction in latency and 1.7x improvement in throughput when compared to a traditional non-partitioned implementation and has comparable performance to that of a custom stored procedure implementation.National Science Foundation (U.S.). Graduate Research Fellowshi
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Murine obscurin and Obsl1 have functionally redundant roles in sarcolemmal integrity, sarcoplasmic reticulum organization, and muscle metabolism.
Biological roles of obscurin and its close homolog Obsl1 (obscurin-like 1) have been enigmatic. While obscurin is highly expressed in striated muscles, Obsl1 is found ubiquitously. Accordingly, obscurin mutations have been linked to myopathies, whereas mutations in Obsl1 result in 3M-growth syndrome. To further study unique and redundant functions of these closely related proteins, we generated and characterized Obsl1 knockouts. Global Obsl1 knockouts are embryonically lethal. In contrast, skeletal muscle-specific Obsl1 knockouts show a benign phenotype similar to obscurin knockouts. Only deletion of both proteins and removal of their functional redundancy revealed their roles for sarcolemmal stability and sarcoplasmic reticulum organization. To gain unbiased insights into changes to the muscle proteome, we analyzed tibialis anterior and soleus muscles by mass spectrometry, uncovering additional changes to the muscle metabolism. Our analyses suggest that all obscurin protein family members play functions for muscle membrane systems
The Effects of Inorganic Nitrogen form and Concentration on Wheat Yield and Nutrient Accumulation and Distribution
Inorganic N is available to plants from the soil as ammonium () and nitrate (). We studied how wheat grown hydroponically to senescence in controlled environmental chambers is affected by N form ( vs. ) and concentration (“subambient,” “ambient,” and “elevated”) in terms of biomass, yield, and nutrient accumulation and partitioning. Wheat supplied with as a sole N source had the strongest response to concentration. Plants exposed to subambient and ambient concentrations typically had the greatest biomass and nutrient accumulation under both N forms. In general -supplied plants had higher concentrations of total N, P, K, S, Ca, Zn, Fe, and Cu, while -supplied plants had higher concentrations of Mg, B, Mn, and - N. -supplied plants contained amounts of phytate similar to -supplied plants but had higher bioavailable Zn, which could have consequences for human health. -supplied plants allocated more nutrients and biomass to aboveground tissues whereas -supplied plants allocated more nutrients to the roots. The two inorganic nitrogen forms influenced plant growth and nutrient status so distinctly that they should be treated as separate nutrients. Moreover, plant growth and nutrient status varied in a non-linear manner with atmospheric concentration
Advanced aeroservoelastic stabilization techniques for hypersonic flight vehicles
Advanced high performance vehicles, including Single-Stage-To-Orbit (SSTO) hypersonic flight vehicles, that are statically unstable, require higher bandwidth flight control systems to compensate for the instability resulting in interactions between the flight control system, the engine/propulsion dynamics, and the low frequency structural modes. Military specifications, such as MIL-F-9490D and MIL-F-87242, tend to limit treatment of structural modes to conventional gain stabilization techniques. The conventional gain stabilization techniques, however, introduce low frequency effective time delays which can be troublesome from a flying qualities standpoint. These time delays can be alleviated by appropriate blending of gain and phase stabilization techniques (referred to as Hybrid Phase Stabilization or HPS) for the low frequency structural modes. The potential of using HPS for compensating structural mode interaction was previously explored. It was shown that effective time delay was significantly reduced with the use of HPS; however, the HPS design was seen to have greater residual response than a conventional gain stablized design. Additional work performed to advance and refine the HPS design procedure, to further develop residual response metrics as a basis for alternative structural stability specifications, and to develop strategies for validating HPS design and specification concepts in manned simulation is presented. Stabilization design sensitivity to structural uncertainties and aircraft-centered requirements are also assessed
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