1,057 research outputs found
Equations for solar tracking
Direct Sun light absorption by trace gases can be used to quantify them and
investigate atmospheric chemistry. In such experiments, the main optical
apparatus is often a grating or a Fourier transform spectrometer. A solar
tracker based on motorized rotating mirrors is also needed to direct the light
along the spectrometer axis, correcting for the apparent rotation of the Sun.
Calculating the Sun azimuth and altitude for a given time and location can be
achieved with high accuracy but different sources of angular offsets appear in
practice when positioning the mirrors. A feedback on the motors, using a light
position sensor closed to the spectrometer is almost always needed. This paper
aims to gather the main geometrical formulas necessary for the use of a widely
used kind of solar tracker, based on two 45{\deg} mirrors in altazimuthal
set-up with a light sensor on the spectrometer, and to illustrate them with a
tracker developed for atmospheric research by our group.Comment: 14 pages, 7 figures. Second version of the paper as published in
Sensors. Main correction: a rotation matrix converted to a reflection matrix.
Main addition: a discussion on how the control theory applies to this kind of
tracking syte
Electrophysiological Correlates of Reading the Single- and Interactive-Mind
Understanding minds is the cognitive basis of successful social interaction. In everyday life, human mental activity often happens at the moment of social interaction among two or multiple persons instead of only one-person. Understanding the interactive mind of two- or multi-person is more complex and higher than understanding the single-person mind in the hierarchical structure of theory of mind. Understanding the interactive mind maybe differentiate from understanding the single mind. In order to examine the dissociative electrophysiological correlates of reading the single mind and reading the interactive mind, the 64 channels event-related potentials were recorded while 16 normal adults were observing three kinds of Chinese idioms depicted physical scenes, one-person with mental activity, and two- or multi-person with mental interaction. After the equivalent N400, in the 500- to 700-ms epoch, the mean amplitudes of late positive component (LPC) over frontal for reading the single mind and reading the interactive mind were significantly more positive than for physical representation, while there was no difference between the former two. In the 700- to 800-ms epoch, the mean amplitudes of LPC over frontal–central for reading the interactive mind were more positive than for reading the single mind and physical representation, while there was no difference between the latter two. The present study provides electrophysiological signature of the dissociations between reading the single mind and reading the interactive mind
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Methionine Adenosyltransferase 1a (MAT1A) Enhances Cell Survival During Chemotherapy Treatment and is Associated with Drug Resistance in Bladder Cancer PDX Mice.
Bladder cancer is among the top ten most common cancers, with about ~380,000 new cases and ~150,000 deaths per year worldwide. Tumor relapse following chemotherapy treatment has long been a significant challenge towards completely curing cancer. We have utilized a patient-derived bladder cancer xenograft (PDX) platform to characterize molecular mechanisms that contribute to relapse following drug treatment in advanced bladder cancer. Transcriptomic profiling of bladder cancer xenograft tumors by RNA-sequencing analysis, before and after relapse, following a 21-day cisplatin/gemcitabine drug treatment regimen identified methionine adenosyltransferase 1a (MAT1A) as one of the significantly upregulated genes following drug treatment. Survey of patient tumor sections confirmed elevated levels of MAT1A in individuals who received chemotherapy. Overexpression of MAT1A in 5637 bladder cancer cells increased tolerance to gemcitabine and stalled cell proliferation rates, suggesting MAT1A upregulation as a potential mechanism by which bladder cancer cells persist in a quiescent state to evade chemotherapy
Phenomenological study on the significance of the scalar potential and Lamb shift
We indicated in our previous work that for QED the contributions of the
scalar potential which appears at the loop level is much smaller than that of
the vector potential and in fact negligible. But the situation may be different
for QCD, one reason is that the loop effects are more significant because
is much larger than , and secondly the non-perturbative QCD
effects may induce the scalar potential. In this work, we phenomenologically
study the contribution of the scalar potential to the spectra of charmonia.
Taking into account both vector and scalar potentials, by fitting the well
measured charmonia spectra, we re-fix the relevant parameters and test them by
calculating other states of the charmonia family. We also consider the role of
the Lamb shift and present the numerical results with and without involving the
Lamb shift
Production of the neutral top-pion in association with a high- jet at the
In the framework of the topcolor-assisted technicolor model, we study
production of the neutral top-pion in association with a
high- jet at the , which proceeds via the partonic processes
, ,
, , and . We find
that it is very challenging to detect the neutral top-pion via
the process , while the
possible signatures of might be detected via the process
at the .Comment: 13 pages, 4 figures; typos correcte
Hydroelastic investigation on a pile breakwater integrated with a flexible tail for long-wave attenuation
A novel concept of wave attenuator is proposed for the defense of long waves, through integrating a flexible tail to the lee-side surface of a pile breakwater. The flexible tail works as a floating blanket made up of hinged blocks, whose scale and stiffness can be easily adjusted. A two-phase-flow numerical model is established based on the open-source computational fluid dynamics (CFD) code OpenFOAM to investigate its wave attenuation performance. Incompressible Navier—Stokes equations are solved in the fluid domain, where an additional computational solid mechanics (CSM) solver is embedded to describe the elastic deformation of the floating tail. The coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming body. The accuracy of the numerical model is validated through comparison with experimental data. Effects of the flexible tail on performance of the pile breakwater are investigated systematically. Dynamic behaviours of the tail are examined, and characteristics of its natural frequency are identified. For safety reasons, the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially examined. It is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater. A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile breakwater. The maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail
Comparison of s- and d-wave gap symmetry in nonequilibrium superconductivity
Recent application of ultrafast pump/probe optical techniques to
superconductors has renewed interest in nonequilibrium superconductivity and
the predictions that would be available for novel superconductors, such as the
high-Tc cuprates. We have reexamined two of the classical models which have
been used in the past to interpret nonequilibrium experiments with some
success: the mu* model of Owen and Scalapino and the T* model of Parker.
Predictions depend on pairing symmetry. For instance, the gap suppression due
to excess quasiparticle density n in the mu* model, varies as n^{3/2} in d-wave
as opposed to n for s-wave. Finally, we consider these models in the context of
S-I-N tunneling and optical excitation experiments. While we confirm that
recent pump/probe experiments in YBCO, as presently interpreted, are in
conflict with d-wave pairing, we refute the further claim that they agree with
s-wave.Comment: 14 pages, 11 figure
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