34,439 research outputs found
Sub-100 attoseconds optics-to-microwave synchronization
We use two fiber-based femtosecond frequency combs and a low-noise carrier
suppression phase detection system to characterize the optical to microwave
synchronization achievable with such frequency divider systems. By applying
specific noise reduction strategies, a residual phase noise as low as -120
dBc/Hz at 1 Hz offset frequency from a 11.55 GHz carrier is measured. The
fractional frequency instability from a single optical-to-frequency divider is
1.1E-16 at 1 s averaging down to below 2E-19 after only 1000 s. The
corresponding rms time deviation is lower than 100 attoseconds up to 1000 s
averaging duration.Comment: 4 pages, 3 figure
Magnetic Phase Diagram of the Hole-doped CaNaCuOCl Cuprate Superconductor
We report on the magnetic phase diagram of a hole-doped cuprate
CaNaCuOCl, which is free from buckling of CuO
planes, determined by muon spin rotation and relaxation. It is characterized by
a quasi-static spin glass-like phase over a range of sodium concentration
(), which is held between long range antiferromagnetic
(AF) phase () and superconducting phase where the system is
non-magnetic for . The obtained phase diagram qualitatively agrees
well with that commonly found for hole-doped high-\tc cuprates, strongly
suggesting that the incomplete suppression of the AF order for is an
essential feature of the hole-doped cuprates.Comment: 5 pages, submitted to Phys. Rev. Let
Pharmacological induction of leukotriene B4 12-hydroxydehydrogenase (LTB4DH) in human neutrophils and its potential in the treatment of myocardial injury
Oral Presentation: Session S29 - Vascular Biology, Basic Research: abstract no. 263postprint16th World Congress on Heart Disease, International Academy of Cardiology, Annual Scientific Sessions, Vancouver, BC, Canada, 23-26 July 2011, Oral Presentation: Session S29: Vascular Biology, Basic Research, Abstract No. 26
Theories and Models for Internet Quality of Service
We survey recent advances in theories and models for Internet Quality of Service (QoS). We start with the theory of network calculus, which lays the foundation for support of deterministic performance guarantees in networks, and illustrate its applications to integrated services, differentiated services, and streaming media playback delays. We also present mechanisms and architecture for scalable support of guaranteed services in the Internet, based on the concept of a stateless core. Methods for scalable control operations are also briefly discussed. We then turn our attention to statistical performance guarantees, and describe several new probabilistic results that can be used for a statistical dimensioning of differentiated services. Lastly, we review recent proposals and results in supporting performance guarantees in a best effort context. These include models for elastic throughput guarantees based on TCP performance modeling, techniques for some quality of service differentiation without access control, and methods that allow an application to control the performance it receives, in the absence of network support
China CO2 emission accounts 1997–2015
China is the world’s top energy consumer and CO2 emitter, accounting for 30% of global emissions. Compiling an accurate accounting of China’s CO2 emissions is the first step in implementing reduction policies. However, no annual, officially published emissions data exist for China. The current emissions estimated by academic institutes and scholars exhibit great discrepancies. The gap between the different emissions estimates is approximately equal to the total emissions of the Russian Federation (the 4th highest emitter globally) in 2011. In this study, we constructed the time-series of CO2 emission inventories for China and its 30 provinces. We followed the Intergovernmental Panel on Climate Change (IPCC) emissions accounting method with a territorial administrative scope. The inventories include energy-related emissions (17 fossil fuels in 47 sectors) and process-related emissions (cement production). The first version of our dataset presents emission inventories from 1997 to 2015. We will update the dataset annually. The uniformly formatted emission inventories provide data support for further emission-related research as well as emissions reduction policy-making in China
High-redshift star formation rate up to z~8.3 derived from gamma-ray bursts and influence of background cosmology
The high-redshift star formation rate (SFR) is difficult to measure directly
even by modern approaches. Long-duration gamma-ray bursts (GRBs) can be
detected to the edge of the visible universe because of their high
luminorsities. The collapsar model of long gamma-ray bursts indicates that they
may trace the star formation history. So long gamma-ray bursts may be a useful
tool of measuring the high-redshift SFR. Observations show that long gamma-ray
bursts prefer to form in a low-metallicity environment. We study the
high-redshift SFR up to z~8.3 considering the Swift GRBs tracing the star
formation history and the cosmic metallicity evolution in different background
cosmological models including CDM, quintessence, quintessence with a
time-varying equation of state, and brane-world model. We use latest Swift GRBs
including two highest- GRBs, GRB 080913 at and GRB 090423 at
. We find that the SFR at shows a steep decay with a slope of
in CDM. In the other three models, the high-redshift SFR
is slightly different from CDM model, and also shows a steep decay.Comment: 5 pages, 5 figures, 2 tables, two references adde
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