4,433 research outputs found
The Obligation to Participate in Biomedical Research
The current prevailing view is that participation in biomedical research is
above and beyond the call of duty. While some commentators have offered
reasons against this, we propose a novel public goods argument for an obligation
to participate in biomedical research. Biomedical knowledge is a public
good, available to any individual even if that individual does not contribute
to it. Participation in research is a critical way to support an important
public good. Consequently, all have a duty to participate. The current social
norm is that individuals participate only if they have a good reason to do so.
The public goods argument implies that individuals should participate unless
they have a good reason not to. Such a shift would be of great aid to the
progress of biomedical research, eventually making society significantly
healthier and longer lived
Multi-plectoneme phase of double-stranded DNA under torsion
We use the worm-like chain model to study supercoiling of DNA under tension
and torque. The model reproduces experimental data for a much broader range of
forces, salt concentrations and contour lengths than previous approaches. Our
theory shows, for the first time, how the behavior of the system is controlled
by a multi-plectoneme phase in a wide range of parameters. This phase does not
only affect turn-extension curves but also leads to a non-constant torque in
the plectonemic phase. Shortcomings from previous models and inconsistencies
between experimental data are resolved in our theory without the need of
adjustable parameters.Comment: 4 pages, 6 figures, submitted, 2 typo's corrected, one reference
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Workshop on Workload and Training, and Examination of their Interactions: Executive summary
The goal of the workshop was to bring together experts in the fields of workload and training and representatives from the Dept. of Defense and industrial organizations who are reponsible for specifying, building, and managing advanced, complex systems. The challenging environments and requirements imposed by military helicopter missions and space station operations were presented as the focus for the panel discussions. The workshop permitted a detailed examination of the theoretical foundations of the fields of training and workload, as well as their practical applications. Furthermore, it created a forum where government, industry, and academic experts were able to examine each other's concepts, values, and goals. The discussions pointed out the necessity for a more efficient and effective flow of information among the groups respresented. The executive summary describes the rationale of the meeting, summarizes the primary points of discussion, and lists the participants and some of their summary comments
U-duality in three and four dimensions
Using generalised geometry we study the action of U-duality acting in three
and four dimensions on the bosonic fields of eleven dimensional supergravity.
We compare the U-duality symmetry with the T-duality symmetry of double field
theory and see how the and SL(5) U-duality groups reduce
to the SO(2,2) and SO(3,3) T-duality symmetry groups of the type IIA theory. As
examples we dualise M2-branes, both black and extreme. We find that uncharged
black M2-branes become charged under U-duality, generalising the Harrison
transformation, while extreme M2-branes will become new extreme M2-branes. The
resulting tension and charges are quantised appropriately if we use the
discrete U-duality group .Comment: v1: 35 pages; v2: minor corrections in section 4.1.2, many references
added; v3: further discussion added on the conformal factor of the
generalised metric in section 2 and on the Wick-rotation used to construct
examples in section
Active Carboxylic Acid-Terminated Alkanethiol Self-Assembled Monolayers on Gold Bead Electrodes for Immobilization of Cytochromes c
It is extremely difficult to immobilize cytochrome c (cyt c) on carboxylic acid-terminated alkanethiol self-assembled monolayers (HOOC-SAM) on gold bead electrodes prepared in a hydrogen flame. We found that simple pretreatment of a HOOC-SAM/gold bead electrode by potential cycling in buffer solution in the range ±300 mV prior to immobilization of the protein facilitated stable cyt c binding to HOOC-SAMs. The stability of cyt c on the HOOC-SAMs is independent of the topology of the gold surface
The 3.3 micron emission feature: Map of the galactic disk, 10 deg less than 1 less than 35 deg, - 6 deg less than b less than 6 deg
The 3.3 micron aromatic feature has been detected in the diffuse galactic emission with the AROME balloon-borne instrument. The results are presented in the form of an map of the 3.3 micron feature's intensity. The AROME instrument consists in a Cassegrain telescope with wobbling secondary mirrors and a liquid/solid nitrogen cooled photometer. The instrumental output is modified by the impulse response of the system. So the galactic surface brightness was restored in Fourier space by an inverse optimal filtering. The map of the feature's intensity is presented for a region of galactic coordinates. All the known H II giant molecular cloud complexes are visible in the 3.3 micron feature emission showing a good correlation with the infrared dust emission
Optimal Quantum Measurements of Expectation Values of Observables
Experimental characterizations of a quantum system involve the measurement of
expectation values of observables for a preparable state |psi> of the quantum
system. Such expectation values can be measured by repeatedly preparing |psi>
and coupling the system to an apparatus. For this method, the precision of the
measured value scales as 1/sqrt(N) for N repetitions of the experiment. For the
problem of estimating the parameter phi in an evolution exp(-i phi H), it is
possible to achieve precision 1/N (the quantum metrology limit) provided that
sufficient information about H and its spectrum is available. We consider the
more general problem of estimating expectations of operators A with minimal
prior knowledge of A. We give explicit algorithms that approach precision 1/N
given a bound on the eigenvalues of A or on their tail distribution. These
algorithms are particularly useful for simulating quantum systems on quantum
computers because they enable efficient measurement of observables and
correlation functions. Our algorithms are based on a method for efficiently
measuring the complex overlap of |psi> and U|psi>, where U is an implementable
unitary operator. We explicitly consider the issue of confidence levels in
measuring observables and overlaps and show that, as expected, confidence
levels can be improved exponentially with linear overhead. We further show that
the algorithms given here can typically be parallelized with minimal increase
in resource usage.Comment: 22 page
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