6,407 research outputs found
A method of isolating organic compounds present in water
Water sample is passed through a column containing macroreticular resin, which absorbs only nonionic organic compounds. These compounds are selectively separated using aqueous eluents of varying pH, or completely exuded with small amount of an organic eluent
Scholastic Probation and Size of High School
In recent years, much attention has been focused on school reorganization in Iowa (cf. Midland Schools, October and No\·- ember, 1953; \u27\u27The Iowan, December-January, 1953-54, and April.May, 1954.) Some proponents of reorganization claim that the small high school (a high school with total enrollment of less than 100 pupils) is not adequately preparing students for college. If true, it is to be expected that this would result in poor grades at the college len:l. One approach would be to determine whether or not there is a relationship between size of high school and scholastic probation. If it were established that there is a highly significant statistical relationship between high school size and probation, then a further study as to cause or causes would be indicated. Specifically, this investigation was concerned with the relationship of the small vs. the large high school and scholastic probation at Iowa State College. Stated as a question in terms of a popular criticism: Do we find an undue proportion of students from small high schools on probation at Iowa State College
Retrieval of surface-layer moisture fields using CSU radars
The surface-layer refractivity, i.e., the refractive index of air near the earth's surface, can be retrieved from radar by examining the phase of stationary ground targets. The index of refraction is a function of pressure, temperature, and humidity, and variations are dominated by humidity in warmer weather. Since the refractivity has a significant impact on the phase of propagating radar waves, it can be measured by observing the range integrated phase change between two stationary ground targets. This index, in turn, can be used to estimate the water vapor near the surface to explore convective storm initiation and storm evolution, and to enhance quantitative precipitation forecasts. This procedure was recently performed using the CSU-CHILL and Pawnee s-band radars, in addition to several other radars and sensors in Colorado. Estimated refractivity fields and the result of automatic stationary target identification are presented as well as phase comparisons with an x-band radar
Towards Causal {VQA}: {R}evealing and Reducing Spurious Correlations by Invariant and Covariant Semantic Editing
Despite significant success in Visual Question Answering (VQA), VQA models have been shown to be notoriously brittle to linguistic variations in the questions. Due to deficiencies in models and datasets, today's models often rely on correlations rather than predictions that are causal w.r.t. data. In this paper, we propose a novel way to analyze and measure the robustness of the state of the art models w.r.t semantic visual variations as well as propose ways to make models more robust against spurious correlations. Our method performs automated semantic image manipulations and tests for consistency in model predictions to quantify the model robustness as well as generate synthetic data to counter these problems. We perform our analysis on three diverse, state of the art VQA models and diverse question types with a particular focus on challenging counting questions. In addition, we show that models can be made significantly more robust against inconsistent predictions using our edited data. Finally, we show that results also translate to real-world error cases of state of the art models, which results in improved overall performanc
Quantum simulation of the spin-boson model with a microwave circuit
We consider superconducting circuits for the purpose of simulating the
spin-boson model. The spin-boson model consists of a single two-level system
coupled to bosonic modes. In most cases, the model is considered in a limit
where the bosonic modes are sufficiently dense to form a continuous spectral
bath. A very well known case is the ohmic bath, where the density of states
grows linearly with the frequency. In the limit of weak coupling or large
temperature, this problem can be solved numerically. If the coupling is strong,
the bosonic modes can become sufficiently excited to make a classical
simulation impossible. Here, we discuss how a quantum simulation of this
problem can be performed by coupling a superconducting qubit to a set of
microwave resonators. We demonstrate a possible implementation of a continuous
spectral bath with individual bath resonators coupling strongly to the qubit.
Applying a microwave drive scheme potentially allows us to access the
strong-coupling regime of the spin-boson model. We discuss how the resulting
spin relaxation dynamics with different initialization conditions can be probed
by standard qubit-readout techniques from circuit quantum electrodynamics.Comment: 23 pages, 10 figure
Frobenius-Perron Resonances for Maps with a Mixed Phase Space
Resonances of the time evolution (Frobenius-Perron) operator P for phase
space densities have recently been shown to play a key role for the
interrelations of classical, semiclassical and quantum dynamics. Efficient
methods to determine resonances are thus in demand, in particular for
Hamiltonian systems displaying a mix of chaotic and regular behavior. We
present a powerful method based on truncating P to a finite matrix which not
only allows to identify resonances but also the associated phase space
structures. It is demonstrated to work well for a prototypical dynamical
system.Comment: 5 pages, 2 figures, 2nd version as published (minor changes
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