30,176 research outputs found
Prompt photon processes in photoproduction at HERA
We present results for the photoproduction of inclusive prompt photons and
for prompt photons accompanied by jets, measured with the ZEUS detector at
HERA. Cross sections as a function of pseudorapidity and transverse energy are
presented for 5 5 GeV in the centre of mass
energy range 120-270 GeV. Comparisons are made with predictions from leading
logarithm parton shower Monte Carlos and next-to-leading order QCD calculations
using currently available models of the photon structure. NLO QCD calculations
describe the shape and magnitude of the measurements reasonably well.Comment: Talk given at Photon99 Conference, Freiburg, German
Distributed digital signal processors for multi-body structures
Several digital filter designs were investigated which may be used to process sensor data from large space structures and to design digital hardware to implement the distributed signal processing architecture. Several experimental tests articles are available at NASA Langley Research Center to evaluate these designs. A summary of some of the digital filter designs is presented, an evaluation of their characteristics relative to control design is discussed, and candidate hardware microcontroller/microcomputer components are given. Future activities include software evaluation of the digital filter designs and actual hardware inplementation of some of the signal processor algorithms on an experimental testbed at NASA Langley
URBAN STRUCTURE: ITS ROLE IN URBAN GROWTH, NET NEW BUSINESS FORMATION AND INDUSTRIAL CHURN
Cities are the “engines of growth” because entrepreneurial and cre-ative activities are concentrated in cities. This suggests that cities grow by host-ing new businesses and “churning” industries advantageously. In so doing, cities need to adapt their spatial structure to mitigate negative externalities. Our previous paper (Lee and Gordon 2007) found that the links between urban structure and growth vary across metro size: more clustering in small metros and more dispersion in large metros were associated with faster employment growth. In this paper, we extend our research to investigate to what extent ur-ban spatial structure variables – dispersion and polycentricity – influence net new business formation (NNBF) and industrial “churning” in a cross-section of 79 U.S. metropolitan areas in the 2000s. The results of least squares regression and locally weighted regression analyses are mixed. OLS results for recent years fail to replicate our results for the 1990s. But applying a more powerful LOESS approach does give results for spatial impacts on NNBF and industrial churning that are consistent with the links between spatial structure and urban growth found in the earlier paper.URBAN SPATIAL STRUCTURE, URBAN GROWTH, NET NEW BUSINESS FORMATION (NNBF), INDUSTRIAL CHURN
Achieving a Student-Teacher Dialectic in Public Secondary Schools: State Legislatures Must Promote Value-Positive Education
SB86-13/14: Senator Credit Hours
SB86-13/14: Senator Credit Hours. This resolution was tabled during the April 16, 2014 meeting of the Associated Students of the University of Montana (ASUM)
Frequency domain state-space system identification
An algorithm for identifying state-space models from frequency response data of linear systems is presented. A matrix-fraction description of the transfer function is employed to curve-fit the frequency response data, using the least-squares method. The parameters of the matrix-fraction representation are then used to construct the Markov parameters of the system. Finally, state-space models are obtained through the Eigensystem Realization Algorithm using Markov parameters. The main advantage of this approach is that the curve-fitting and the Markov parameter construction are linear problems which avoid the difficulties of nonlinear optimization of other approaches. Another advantage is that it avoids windowing distortions associated with other frequency domain methods
Generalized Unitary Coupled Cluster Wavefunctions for Quantum Computation
We introduce a unitary coupled-cluster (UCC) ansatz termed -UpCCGSD that
is based on a family of sparse generalized doubles (D) operators which provides
an affordable and systematically improvable unitary coupled-cluster
wavefunction suitable for implementation on a near-term quantum computer.
-UpCCGSD employs products of the exponential of pair coupled-cluster
double excitation operators (pCCD), together with generalized single (S)
excitation operators. We compare its performance in both efficiency of
implementation and accuracy with that of the generalized UCC ansatz employing
the full generalized SD excitation operators (UCCGSD), as well as with the
standard ansatz employing only SD excitations (UCCSD). -UpCCGSD is found to
show the best scaling for quantum computing applications, requiring a circuit
depth of , compared with for UCCGSD and
for UCCSD where is the number of spin
orbitals and is the number of electrons. We analyzed the accuracy of
these three ans\"atze by making classical benchmark calculations on the ground
state and the first excited state of H (STO-3G, 6-31G), HO (STO-3G),
and N (STO-3G), making additional comparisons to conventional coupled
cluster methods. The results for ground states show that -UpCCGSD offers a
good tradeoff between accuracy and cost, achieving chemical accuracy for lower
cost of implementation on quantum computers than both UCCGSD and UCCSD. Excited
states are calculated with an orthogonally constrained variational quantum
eigensolver approach. This is seen to generally yield less accurate energies
than for the corresponding ground states. We demonstrate that using a
specialized multi-determinantal reference state constructed from classical
linear response calculations allows these excited state energetics to be
improved
La rêverie comme expérience esthétique et spirituelle chez Jean-Jacques Rousseau
Le présent article propose une réflexion sur les multiples dimensions du concept de rêverie et sur les conditions entourant l’expérience esthétique telles qu’elles apparaissent dans Les Rêveries du promeneur solitaire. En filigrane, nous tentons également de positionner ce recueil dans la philosophie esthétique du siècle de Lumières. Au fond, la thèse centrale ici est que chez Rousseau la contemplation de la nature devient, dans les bonnes conditions, une expérience esthétique où l’imagination transpose l’esprit dans un état qui s’approche du mysticisme
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