27,398 research outputs found
Transitive probabilistic CLIR models.
Transitive translation could be a useful technique to enlarge the number of supported language pairs for a cross-language information retrieval (CLIR) system in a cost-effective manner. The paper describes several setups for transitive translation based on probabilistic translation models. The transitive CLIR models were evaluated on the CLEF test collection and yielded a retrieval effectiveness\ud
up to 83% of monolingual performance, which is significantly better than a baseline using the synonym operator
Evaluation of salmon and steelhead spawning habitat quality in the South Fork Trinity River Basin, 1997
Sediment sampling was used to evaluate chinook salmon
(Oncorhynchus tshawytscha) and steelhead (O. mykiss) spawning habitat quality in the South Fork Trinity River (SFTR) basin. Sediment samples were collected using a McNeil-type sampler and wet sieved through a series of Tyler screens (25.00 mm, 12.50 mm, 6.30 mm, 3.35 mm, 1.00 mm, and 0.85 mm). Fines (particles < 0.85 mm) were determined after a l0-minute settling period in Imhoff cones. Thirteen stations were sampled in the SFTR basin: five stations were located in mainstem SFTR between rk 2.1 and 118.5, 2 stations each were located in EF of the SFTR, Grouse Creek, and Madden Creek, and one station each was located in Eltapom and Hayfork Creeks. Sample means for fines(particles < 0.85 mm) fer SFTR stations ranged between
14.4 and 19.4%; tributary station sample mean fines ranged between 3.4 and 19.4%. Decreased egg survival would be expected at 4 of 5 mainstem SFTR stations and at one station in EF of SFTR and Grouse Creek where fines content exceed 15%. Small gravel/sand content measured at all stations were high, and exceed levels associated with reduced sac fry emergence rates. Reduction of egg survival or sac fry emergence due to sedimentation in spawning gravels could lead to reduced juvenile production from the South Fork Trinity River.
(PDF contains 18 pages.
National and international freight transport models: overview and ideas for further development
This paper contains a review of the literature on freight transport models, focussing on the types of models that have been developed since the nineties for forecasting, policy simulation and project evaluation at the national and international level. Models for production, attraction, distribution, modal split and assignment are discussed in the paper. Furthermore, the paper also includes a number of ideas for future development, especially for the regional and urban components within national freight transport models
Classical Optimizers for Noisy Intermediate-Scale Quantum Devices
We present a collection of optimizers tuned for usage on Noisy Intermediate-Scale Quantum (NISQ) devices. Optimizers have a range of applications in quantum computing, including the Variational Quantum Eigensolver (VQE) and Quantum Approximate Optimization (QAOA) algorithms. They are also used for calibration tasks, hyperparameter tuning, in machine learning, etc. We analyze the efficiency and effectiveness of different optimizers in a VQE case study. VQE is a hybrid algorithm, with a classical minimizer step driving the next evaluation on the quantum processor. While most results to date concentrated on tuning the quantum VQE circuit, we show that, in the presence of quantum noise, the classical minimizer step needs to be carefully chosen to obtain correct results. We explore state-of-the-art gradient-free optimizers capable of handling noisy, black-box, cost functions and stress-test them using a quantum circuit simulation environment with noise injection capabilities on individual gates. Our results indicate that specifically tuned optimizers are crucial to obtaining valid science results on NISQ hardware, and will likely remain necessary even for future fault tolerant circuits
Sub-Poissonian Shot Noise In A Diffusive Conductor
A review is given of the shot-noise properties of metallic, diffusive
conductors. The shot noise is one third of the Poisson noise, due to the
bimodal distribution of transmission eigenvalues. The same result can be
obtained from a semiclassical calculation. Starting from Oseledec's theorem it
is shown that the bimodal distribution is required by Ohm's law.Comment: 9 pages, LaTeX, including 2 figure
Doubled Shot Noise In Disordered Normal-Metal-Superconductor Junctions
The low-frequency shot-noise power of a normal-metal-superconductor junction
is studied for arbitrary normal region. Through a scattering approach, a
formula is derived which expresses the shot-noise power in terms of the
transmission eigenvalues of the normal region. The noise power divided by the
current is enhanced by a factor two with respect to its normal-state value, due
to Cooper-pair transport in the superconductor. For a disordered normal region,
it is still smaller than the Poisson noise, as a consequence of noiseless open
scattering channels.Comment: 4 pages, RevTeX v3.0, including 1 figure, Submitted to Physical
Review
Searching Spontaneous Conversational Speech
The ACM SIGIR Workshop on Searching Spontaneous Conversational Speech was held as part of the 2007 ACM SIGIR Conference in Amsterdam.\ud
The workshop program was a mix of elements, including a keynote speech, paper presentations and panel discussions. This brief report describes the organization of this workshop and summarizes the discussions
Unfolding Quantum Computer Readout Noise
In the current era of noisy intermediate-scale quantum (NISQ) computers,
noisy qubits can result in biased results for early quantum algorithm
applications. This is a significant challenge for interpreting results from
quantum computer simulations for quantum chemistry, nuclear physics, high
energy physics, and other emerging scientific applications. An important class
of qubit errors are readout errors. The most basic method to correct readout
errors is matrix inversion, using a response matrix built from simple
operations to probe the rate of transitions from known initial quantum states
to readout outcomes. One challenge with inverting matrices with large
off-diagonal components is that the results are sensitive to statistical
fluctuations. This challenge is familiar to high energy physics, where
prior-independent regularized matrix inversion techniques (`unfolding') have
been developed for years to correct for acceptance and detector effects when
performing differential cross section measurements. We study various unfolding
methods in the context of universal gate-based quantum computers with the goal
of connecting the fields of quantum information science and high energy physics
and providing a reference for future work. The method known as iterative
Bayesian unfolding is shown to avoid pathologies from commonly used matrix
inversion and least squares methods.Comment: 13 pages, 16 figures; v2 has a typo fixed in Eq. 3 and a series of
minor modification
Diquaternary Ammonium Compounds in Zeolite Synthesis: Cyclic and Polycyclic N-Heterocycles Connected by Methylene Chains
An additional dimension has been added to our long-standing studies in high silica zeolite synthesis via a guest/host synergism. We have created and studied the impact of making symmetric diquaternary ammonium compounds, by varying the chain length between nitrogen charge centers, and the heterocycle size and geometry containing the nitrogen. This allows the introduction of a second spatial parameter in the use of the charged organo-cation guest in the zeolite synthesis. The series of 15 diquaternary ammonium compounds (5 heterocycles synthesized onto chain lengths of C4−C6) were tested in a total of 135 zeolite syntheses reactions. Nine screening reactions were employed for each guest molecule, and the conditions built upon past successes in finding novel high silica zeolites via introduction of boron, aluminum, or germanium as substituting tetrahedral framework atoms for silicon. Eighteen different zeolite structures emerged from the studies. The use of specific chain lengths for derivatives of the pyrrolidine ring system produced novel zeolite materials SSZ-74 and 75
Strong Analytic Controllability for Hydrogen Control Systems
The realization and representation of so(4,2) associated with the hydrogen
atom Hamiltonian are derived. By choosing operators from the realization of
so(4,2) as interacting Hamiltonians, a hydrogen atom control system is
constructed, and it is proved that this control system is strongly analytically
controllable based on a time-dependent strong analytic controllability theorem.Comment: 6 pages; corrected typo; added equations in section III for
representation states of so(4,2). accepted by CDC 200
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