10,342 research outputs found
Surface roughness during depositional growth and sublimation of ice crystals
Full version of an earlier discussion paper (Chou et al. 2018)Ice surface properties can modify the scattering properties of atmospheric ice crystals and therefore affect the radiative properties of mixed-phase and cirrus clouds. The Ice Roughness Investigation System (IRIS) is a new laboratory setup designed to investigate the conditions under which roughness develops on single ice crystals, based on their size, morphology and growth conditions (relative humidity and temperature). Ice roughness is quantified through the analysis of speckle in 2-D light-scattering patterns. Characterization of the setup shows that a supersaturation of 20 % with respect to ice and a temperature at the sample position as low as-40 °C could be achieved within IRIS. Investigations of the influence of humidity show that higher supersaturations with respect to ice lead to enhanced roughness and irregularities of ice crystal surfaces. Moreover, relative humidity oscillations lead to gradual ratcheting-up of roughness and irregularities, as the crystals undergo repeated growth-sublimation cycles. This memory effect also appears to result in reduced growth rates in later cycles. Thus, growth history, as well as supersaturation and temperature, influences ice crystal growth and properties, and future atmospheric models may benefit from its inclusion in the cloud evolution process and allow more accurate representation of not just roughness but crystal size too, and possibly also electrification properties.Peer reviewe
Total Cross Section, Inelasticity and Multiplicity Distributions in Proton -- Proton Collisions
Multiparticle production in high energy proton -- proton collisions has been
analysed in the frame of Strongly Correlated Quark Model (SCQM) of the hadron
structure elaborated by the author. It is shown that inelasticity decreases at
high energies and this effect together with the total cross section growth and
the increasing with collision energy the masses of intermediate clusters result
in the violation of KNO -- scaling.Comment: 21 pages, 11 figures, submitted to Yad. Fisik
Engineering a static verification tool for GPU kernels
We report on practical experiences over the last 2.5 years related to the engineering of GPUVerify, a static verification tool for OpenCL and CUDA GPU kernels, plotting the progress of GPUVerify from a prototype to a fully functional and relatively efficient analysis tool. Our hope is that this experience report will serve the verification community by helping to inform future tooling efforts. © 2014 Springer International Publishing
Direct Observation of the Quantum Energy Gap in S = 1/2 Tetragonal Cuprate Antiferromagnets
Using an electron spin resonance spectrometer covering a wide range of
frequency and magnetic field, we have measured the low energy excitations of
the S=1/2 tetragonal antiferromagnets, Sr_{2}CuO_{2}Cl_{2} and
Sr_{2}Cu_{3}O_{4}Cl_{2}. Our observation of in-plane energy gaps of order 0.1
meV at zero external magnetic field are consistent with a spin wave
calculation, which includes several kinds of quantum fluctuations that remove
frustration. Results agree with other experiments and with exchange anisotropy
parameters determined from a five band Hubbard model.Comment: 4 pages, 3 figure
Disoriented Chiral Condensates, Pion Probability Distributions and Parallels with Disordered System
A general expression is discussed for pion probability distributions coming
from relativistic heavy ion collisions. The general expression contains as
limits: 1) The disoriented chiral condensate (DCC), 2) the negative binomial
distribution and Pearson type III distribution, 3) a binomial or Gaussian
result, 4) and a Poisson distribution. This general expression approximates
other distributions such as a signal to noise laser distribution. Similarities
and differences of the DCC distribution with these other distribution are
studied. A connection with the theory of disordered systems will be discussed
which include spin-glasses, randomly broken objects, random and chaotic maps.Comment: 5 pages, 1 figure include
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