Search results for "dynamiikka"
showing 10 items of 232 documents
Light-nuclei gluons from dijet production in proton-oxygen collisions
2022
The prospects of measuring a single-differential dijet cross section during the proposed short proton-oxygen data taking at LHC Run 3 are studied using next-to-leading-order perturbative QCD predictions. With reasonable experimental cuts and luminosity estimates, such a measurement is found to be feasible, and a few inverse nanobarns of integrated luminosity is estimated to be enough to yield new constraints on parton distribution functions (PDFs) of light nuclei. In the absence of a dedicated proton-proton reference, a mixed-energy nuclear modification ratio is proposed for cancelling free-proton PDF uncertainties to obtain a direct access to the nuclear modifications of the parton distrib…
Massive quarks in NLO dipole factorization for DIS : Transverse photon
2022
We calculate the light cone wave functions for the QCD Fock components in a transverse virtual photon necessary for applications at next-to-leading order in the QCD coupling, including quark masses. We present a detailed calculation of both the one loop wave function for the quark-antiquark Fock component and the tree level wave function for the quark-antiquark-gluon Fock component. The quark masses are renormalized in the pole mass scheme, satisfying constraints from the requirement of Lorentz invariance. In particular the quark Pauli form factor at NLO is recovered from the on-shell limit of the quark-antiquark Fock component. We use our result to calculate the next-to-leading order corre…
Evolution of eccentricities induced by geometrical and quantum fluctuations in proton-nucleus collisions
2023
We compute the azimuthal eccentricities arising from initial stage fluctuations in high energy proton-nucleus collisions at proper times $\tau \geq 0^+$. We consider two sources of fluctuations, namely the geometrical structure of the proton and the fluctuation of color fields carried by both proton and nucleus. Describing these effects with Gaussian models allows us to analytically calculate the one- and two-point correlators of energy density, from which the eccentricities are obtained. We compute the proper time evolution of these quantities by approximating the Glasma dynamics in terms of linearized Yang-Mills equations, which we solve by assuming free field propagation and adopting the…
Proton hot spots and exclusive vector meson production
2022
We explore consequences of the existence of gluonic hot spots inside the proton for coherent and incoherent exclusive vector meson production cross sections in deep inelastic scattering. By working in the dilute limit of the Color Glass Condensate framework to compute the cross sections for Gaussian hot spots of fluctuating color charges and employing a non-relativistic vector meson wave function, we are able to perform large parts of the calculation analytically. We find that the coherent cross section is sensitive to both the size of the target and the structure of the probe. The incoherent cross section is dominated by color fluctuations at small transverse momentum transfer ($t$), by pr…
Speechlessness, anxiety, and confusion in a teacher education student group
2017
The aim of the study was to explore the tensions, as experienced by student teachers, in a teacher education program that is based on psychodynamic theory. Previous research shows that students have had orientation problems in innovative university studies because it involves students having to take steps toward their discomfort zone. It was therefore considered important to study the mismatch or match of the training model and student experiences. The data were gathered through student interviews. The data analysis utilized a case study methodology and proceeded from thematic network analysis toward a deeper interpretation of the data. The analysis shows students struggle to understand the…
Ab initio molecular dynamics study of overtone excitations in formic acid and its water complex
2018
In this article, we present results from ab initio molecular dynamics simulation of overtone excitation in formic acid monomer and its water complex in the gas phase. For the monomer, a conformation change is observed employing both OH and CH vibrational excitations, which supports experimental findings. In the formic acid–water complex, interconversion also takes place, but it proceeds via hydrogen exchange rather than via intramolecular reaction. Simulations raise a question on effect of quantum and matrix effects to the results. Also, a brief test of different computation methods was done on the system. peerReviewed
Thermodynamics of hydronium and hydroxide surface solvation.
2014
[Introduction] The concentration of hydronium and hydroxide at the water-air interface has been under debate for a long time. Recent evidence from a range of experiments and theoretical calculations strongly suggests the water surface is somewhat acidic. Using novel polarizable models we have performed potential of mean force calculations of a hydronium ion, a hydroxide ion and a water molecule in a water droplet and a water slab and we were able to rationalize that hydronium, but not hydroxide, is slightly enriched at the surface for two reasons. First, because the hydrogen-bond acceptance capacity of hydronium is weaker than water it is more favorable to have the hydronium oxygen on the s…
Scalable Constant pH Molecular Dynamics in GROMACS
2022
Molecular dynamics (MD) computer simulations are used routinely to compute atomistic trajectories of complex systems. Systems are simulated in various ensembles, depending on the experimental conditions one aims to mimic. While constant energy, temperature, volume, and pressure are rather straightforward to model, pH, which is an equally important parameter in experiments, is more difficult to account for in simulations. Although a constant pH algorithm based on the λ-dynamics approach by Brooks and co-workers [Kong, X.; Brooks III, C. L. J. Chem. Phys.1996, 105, 2414–2423] was implemented in a fork of the GROMACS molecular dynamics program, uptake has been rather limited, presumably due to…
Thermodynamics of a Phase-Driven Proximity Josephson Junction
2019
We study the thermodynamic properties of a superconductor/normal metal/superconductor Josephson junction {in the short limit}. Owing to the proximity effect, such a junction constitutes a thermodynamic system where {phase difference}, supercurrent, temperature and entropy are thermodynamical variables connected by equations of state. These allow conceiving quasi-static processes that we characterize in terms of heat and work exchanged. Finally, we combine such processes to construct a Josephson-based Otto and Stirling cycles. We study the related performance in both engine and refrigerator operating mode.
Self-employment transitions and alternation in Finnish rural and urban labour markets
2008
. This paper deals with the transitions and alternation between self-employment, paid-employment and non-employment in Finland in 1987–1999, paying special attention to differences in self-employment dynamics between areas characterized by different labour market conditions, viz. rural and urban locations. Markovian analysis reveals significant differences by the type of area in the processes of transition between the three labour market states. Alternation between self-employment and other labour markets states turns out to be greater in rural than urban areas. Five major types of alternating working careers are identified. The type of area is importantly related to alternating working ca…