1,815 research outputs found
Wind sensor
An apparatus is described for sensing the temperature, velocity, and direction of the wind, including four temperature-dependent crystal oscillators spaced about an axis, a heater centered on the axis, and a screen through which the wind blows to pass over the crystals. In one method of operation, the frequency of the oscillators is taken when the heater is not energized, to obtain the temperature of the wind, and the frequencies of the oscillators are taken after the heater is energized to determine the direction and velocity of the wind. When the heater is energized, the wind causes the downwind crystals to achieve a higher temperature than the upwind crystals, and with the magnitude of the difference indicating the velocity of the wind
Pyrheliometric comparisons at the JPL Table Mountain Facility
Calibration and comparative measurements of pyrheliometric instruments using natural sunligh
Quartz crystal microbalance use in biological studies
Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described
Calculation of 3D genome structures for comparison of chromosome conformation capture experiments with microscopy: An evaluation of single-cell Hi-C protocols.
Single-cell chromosome conformation capture approaches are revealing the extent of cell-to-cell variability in the organization and packaging of genomes. These single-cell methods, unlike their multi-cell counterparts, allow straightforward computation of realistic chromosome conformations that may be compared and combined with other, independent, techniques to study 3D structure. Here we discuss how single-cell Hi-C and subsequent 3D genome structure determination allows comparison with data from microscopy. We then carry out a systematic evaluation of recently published single-cell Hi-C datasets to establish a computational approach for the evaluation of single-cell Hi-C protocols. We show that the calculation of genome structures provides a useful tool for assessing the quality of single-cell Hi-C data because it requires a self-consistent network of interactions, relating to the underlying 3D conformation, with few errors, as well as sufficient longer-range cis- and trans-chromosomal contacts
Investigating the trade-off between the effectiveness and efficiency of process modeling
Despite recent efforts to improve the quality of process models, we still observe a significant dissimilarity in quality between models. This paper focuses on the syntactic condition of process models, and how it is achieved. To this end, a dataset of 121 modeling sessions was investigated. By going through each of these sessions step by step, a separate ‘revision’ phase was identified for 81 of them. Next, by cutting the modeling process off at the start of the revision phase, a partial process model was exported for these modeling sessions. Finally, each partial model was compared with its corresponding final model, in terms of time, effort, and the number of syntactic errors made or solved, in search for a possible trade-off between the effectiveness and efficiency of process modeling. Based on the findings, we give a provisional explanation for the difference in syntactic quality of process models
Study of chirally motivated low-energy optical potentials
The optical potential in the nuclear medium is evaluated self
consistently from a free-space matrix constructed within a
coupled-channel chiral approach to the low-energy data. The
chiral-model parameters are fitted to a select subset of the low-energy data
{\it plus} the atomic data throughout the periodic table. The resulting
attractive optical potentials are relatively `shallow', with central
depth of the real part about 55 MeV, for a fairly reasonable reproduction of
the atomic data with . Relatively `deep' attractive
potentials of depth about 180 MeV, which result in other phenomenological
approaches with , are ruled out within chirally
motivated models. Different physical data input is required to distinguish
between shallow and deep optical potentials. The ()
reaction could provide such a test, with exclusive rates differing by over a
factor of three for the two classes of potentials. Finally, forward ()
differential cross sections for the production of relatively narrow deeply
bound {\it nuclear} states are evaluated for deep optical
potentials, yielding values considerably lower than those estimated before.Comment: 22 pages, 3 figures, minor revisions, Nucl. Phys. A in pres
Self-energy of a scalar charge near higher-dimensional black holes
We study the problem of self-energy of charges in higher dimensional static
spacetimes. Application of regularization methods of quantum field theory to
calculation of the classical self-energy of charges leads to model-independent
results. The correction to the self-energy of a scalar charge due to the
gravitational field of black holes of the higher dimensional
Majumdar-Papapetrou spacetime is calculated exactly. It proves to be zero in
even dimensions, but it acquires non-zero value in odd dimensional spacetimes.
The origin of the self-energy correction in odd dimensions is similar to the
origin the conformal anomalies in quantum field theory in even dimensional
spacetimes.Comment: 9 page
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