619 research outputs found
An inertial velocity reference for the NASA airborne Doppler lidar
The following four tasks were studied: (1) modification of the calibration routines to calibrate the Inertial Measurement Unit gyroscope drifts with fixed platform heading; (2) modification of the calibration routines to calibrate the Inertial Measurement Unit accelerometers; (3) checking overall software again for errors; and (4) providing documentation on the above work describing changes to the present software, results of these changes and future operating procedures
3D occlusion recovery using few cameras
We present a practical framework for detecting and modeling 3D static occlusions for wide-baseline, multi-camera scenarios where the number of cameras is small. The framework consists of an iterative learning procedure where at each frame the occlusion model is used to solve the voxel occupancy problem, and this solution is then used to update the occlusion model. Along with this iterative procedure, there are two contributions of the proposed work: (1) a novel energy function (which can be minimized via graph cuts) specifically designed for use in this procedure, and (2) an application that incorporates our probabilistic occlusion model into a 3D tracking system. Both qualitative and quantitative results of the proposed algorithm and its incorporation with a 3D tracker are presented for support. 1
Coupling DNA-binding and ATP hydrolysis in Escherichia coli RecQ: role of a highly conserved aromatic-rich sequence
RecQ enzymes are broadly conserved Superfamily-2 (SF-2) DNA helicases that play critical roles in DNA metabolism. RecQ proteins use the energy of ATP hydrolysis to drive DNA unwinding; however, the mechanisms by which RecQ links ATPase activity to DNA-binding/unwinding are unknown. In many Superfamily-1 (SF-1) DNA helicases, helicase sequence motif III links these activities by binding both single-stranded (ss) DNA and ATP. However, the ssDNA-binding aromatic-rich element in motif III present in these enzymes is missing from SF-2 helicases, raising the question of how these enzymes link ATP hydrolysis to DNA-binding/unwinding. We show that Escherichia coli RecQ contains a conserved aromatic-rich loop in its helicase domain between motifs II and III. Although placement of the RecQ aromatic-rich loop is topologically distinct relative to the SF-1 enzymes, both loops map to similar tertiary structural positions. We examined the functions of the E.coli RecQ aromatic-rich loop using RecQ variants with single amino acid substitutions within the segment. Our results indicate that the aromatic-rich loop in RecQ is critical for coupling ATPase and DNA-binding/unwinding activities. Our studies also suggest that RecQ's aromatic-rich loop might couple ATP hydrolysis to DNA-binding in a mechanistically distinct manner from SF-1 helicases
On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy
The fundamental parameters describing the coronal spectrum of an accreting
black hole are the slope of the power-law continuum and the energy
at which it rolls over. Remarkably, this parameter can be accurately
measured for values as high as 1 MeV by modeling the spectrum of X-rays
reflected from a black hole accretion disk at energies below 100 keV. This is
possible because the details in the reflection spectrum, rich in fluorescent
lines and other atomic features, are very sensitive to the spectral shape of
the hardest coronal radiation illuminating the disk. We show that fitting
simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most
recent version of our reflection model RELXILL, one can obtain reasonable
constraints on at energies from tens of keV up to 1 MeV, for a source
as faint as 1 mCrab in a 100 ks observation.Comment: Accepted for publication in ApJL, 6 pages, 5 figure
Hydrocarbon formation and oxidation in spark-ignition engines
This report summarizes the key results and conceptual findings from
a three year research program on hydrocarbon formation and oxidation
mechanisms in spark-ignition engines. Research was carried out in four
areas: laminar flame quenching experimental and analytical studies;
quench layer studies in a spark-ignition engine using a rapid-acting
gas sampling valve; flow visualization studies in a transparent engine
to determine quench layer and quench crevice gas motion; studies of heat
transfer, mixing and HC oxidation in the exhaust port. More detailed
descriptions of the individual research activities in these areas can
be found in the theses and publications completed to date which form
Volumes II to XI of the final report on this program.Final report on a research program funded by General Motors Research Laboratories, September 1976 to August 1979
The Rate-Controlled Constrained-Equilibrium Approach to Far-From-Local-Equilibrium Thermodynamics
The Rate-Controlled Constrained-Equilibrium (RCCE) method for the description of the time-dependent behavior of dynamical systems in non-equilibrium states is a general, effective, physically based method for model order reduction that was originally developed in the framework of thermodynamics and chemical kinetics. A generalized mathematical formulation is presented here that allows including nonlinear constraints in non-local equilibrium systems characterized by the existence of a non-increasing Lyapunov functional under the system’s internal dynamics. The generalized formulation of RCCE enables to clarify the essentials of the method and the built-in general feature of thermodynamic consistency in the chemical kinetics context. In this paper, we work out the details of the method in a generalized mathematical-physics framework, but for definiteness we detail its well-known implementation in the traditional chemical kinetics framework. We detail proofs and spell out explicit functional dependences so as to bring out and clarify each underlying assumption of the method. In the standard context of chemical kinetics of ideal gas mixtures, we discuss the relations between the validity of the detailed balance condition off-equilibrium and the thermodynamic consistency of the method. We also discuss two examples of RCCE gas-phase combustion calculations to emphasize the constraint-dependent performance of the RCCE method.Fondazione Cariplo (grant 2008-2290)United States. Army Research Office (grant number W911NF-08-1-0444
On a Generalization of the Frobenius Number
We consider a generalization of the Frobenius Problem where the object of
interest is the greatest integer which has exactly representations by a
collection of positive relatively prime integers. We prove an analogue of a
theorem of Brauer and Shockley and show how it can be used for computation.Comment: 5 page
Towards a Unified Theory of Massless Superfields of All Superspins
We describe the ``universal'' action for massless superfields of all
superspins in N = 1, D = 4 anti-de Sitter superspace as a gauge theory of
unconstrained superfields taking their values in the commutative algebra of
analytic functions over a one-sheeted hyperboloid in . The action is
invariant under N = 2 supersymmetry transformations which form a closed algebra
off the mass-shell.Comment: 12 pages, LaTe
Quelles perspectives pour les musées au xxie siècle ?
James Clifford © musée du quai Branly - Jacques Chirac, photo Cyril Zannettacci M. Frédéric KECK C’est un grand plaisir et un grand honneur d’accueillir pour cette conférence inaugurale de notre colloque Le musée du quai Branly dix ans après. Un musée à imaginer, le professeur James Clifford qui est un des observateurs les plus importants des musées d’anthropologie, des circulations d’œuvres, des revendications autochtones depuis une trentaine d’années. James Clifford a fait sa thèse à Harva..
Molecular insights into the prototypical single-stranded DNA-binding protein from E. coli
The SSB protein o
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