1,078 research outputs found
First Long-Term Application of Squeezed States of Light in a Gravitational-Wave Observatory
We report on the first long-term application of squeezed vacuum states of
light to improve the shot-noise-limited sensitivity of a gravitational-wave
observatory. In particular, squeezed vacuum was applied to the German/British
detector GEO600 during a period of three months from June to August 2011, when
GEO600 was performing an observational run together with the French/Italian
Virgo detector. In a second period squeezing application continued for about 11
months from November 2011 to October 2012. During this time, squeezed vacuum
was applied for 90.2% (205.2 days total) of the time that science-quality data
was acquired with GEO600. Sensitivity increase from squeezed vacuum application
was observed broad-band above 400Hz. The time average of gain in sensitivity
was 26% (2.0dB), determined in the frequency band from 3.7kHz to 4.0kHz. This
corresponds to a factor of two increase in observed volume of the universe, for
sources in the kHz region (e.g. supernovae, magnetars). We introduce three new
techniques to enable stable long-term application of squeezed light, and show
that the glitch-rate of the detector did not increase from squeezing
application. Squeezed vacuum states of light have arrived as a permanent
application, capable of increasing the astrophysical reach of
gravitational-wave detectors.Comment: 4 pages, 4 figure
Information and Multi-Period Optimal Income Taxation with Government Commitment
The optimal income taxation problem has been extensively studied in one- period models. When consumers work for many periods, this paper analyzes what information, if any, that the government learns about abilities in one period can be used in later periods to attain more redistribution than in a one- period world. liken the government must commit itself to future tax schedules, the gains cane from relaxing self-selection constraints by intertemporal nonstationarity. The effect of nonstationarity is analogous to that of randomization in one-period models. In a model with two ability classes it is shown that the key use of information is that only a single lifetime self-selection constraint for each type of consumer must be imposed. Sane necessary and sufficient conditions for randomization or nonstationarity are given. The planner can make additional use of the information when individual and social rates of time discounting differ. In this case, the limiting tax schedule is a nondistorting one if the government has a lower discount rate than individuals.
How does a protein search for the specific site on DNA: the role of disorder
Proteins can locate their specific targets on DNA up to two orders of
magnitude faster than the Smoluchowski three-dimensional diffusion rate. This
happens due to non-specific adsorption of proteins to DNA and subsequent
one-dimensional sliding along DNA. We call such one-dimensional route towards
the target "antenna". We studied the role of the dispersion of nonspecific
binding energies within the antenna due to quasi random sequence of natural
DNA. Random energy profile for sliding proteins slows the searching rate for
the target. We show that this slowdown is different for the macroscopic and
mesoscopic antennas.Comment: 4 pages, 4 figure
Estimates for practical quantum cryptography
In this article I present a protocol for quantum cryptography which is secure
against attacks on individual signals. It is based on the Bennett-Brassard
protocol of 1984 (BB84). The security proof is complete as far as the use of
single photons as signal states is concerned. Emphasis is given to the
practicability of the resulting protocol. For each run of the quantum key
distribution the security statement gives the probability of a successful key
generation and the probability for an eavesdropper's knowledge, measured as
change in Shannon entropy, to be below a specified maximal value.Comment: Authentication scheme corrected. Other improvements of presentatio
Complete physical simulation of the entangling-probe attack on the BB84 protocol
We have used deterministic single-photon two qubit (SPTQ) quantum logic to
implement the most powerful individual-photon attack against the
Bennett-Brassard 1984 (BB84) quantum key distribution protocol. Our measurement
results, including physical source and gate errors, are in good agreement with
theoretical predictions for the Renyi information obtained by Eve as a function
of the errors she imparts to Alice and Bob's sifted key bits. The current
experiment is a physical simulation of a true attack, because Eve has access to
Bob's physical receiver module. This experiment illustrates the utility of an
efficient deterministic quantum logic for performing realistic physical
simulations of quantum information processing functions.Comment: 4 pages, 5 figure
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Dynamic Optimal Income Taxation with Government Commitment
Analyzes the optimal income taxation problems of consumers in the United States. Usage of the abilities learned in one period to attain redistribution; Commitment of the government to policies on the intertemporal nonstationarity of tax schedules; Relevance of lesser social discount rate on the rate of individual
Acute respiratory distress syndrome: new definition, current and future therapeutic options.
Since acute respiratory distress syndrome (ARDS) was first described in 1967 there has been large number of studies addressing its pathogenesis and therapies. Despite this intense research activity, there are very few effective therapies for ARDS other than the use of lung protection strategies. This lack of therapeutic modalities is not only related to the complex pathogenesis of this syndrome but also the insensitive and nonspecific diagnostic criteria to diagnose ARDS. This review article will summarize the key features of the new definition of ARDS, and provide a brief overview of innovative therapeutic options that are being assessed in the management of ARDS
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