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Messungen morphologischer Parameter an Potamogetón perfoliatus führten zu zahlreichen positiven Korrelationen wie bereits frühere Untersuchungen an Isoëtes lacustris. Es ergaben sich Übereinstimmungen trotz unterschiedlicher Lebensgeschichte. Abweichungen spiegeln die unterschiedlichen Wachstumsstrategien wider, die die beiden Arten verfolgen. Weitere Korrelationen zeigen die Abhängigkeit der Blattentwicklung bei P. perfoliatus bzw. der Rosettenausbildung bei I. lacustris von Standortbedingungen. Ergänzende Messungen erwiesen, dass eine Reihe von Regressionsgleichungen für weitere 6 Laichkrautarten bzw. 9 Isoëtes-Taxa gültig ist. Ihre besondere Bedeutung haben die erhaltenen Regressionsgleichungen für die zerstörungsfreie Gewinnung von Daten für gefährdete Pflanzenarten und ihre Bestände, beispielsweise den Blattflächenindex; dafür werden Beispiele gegeben.
In this work, largely based on [J. L. Albacete, A. Soto-Ontoso, Hot spots and the hollowness of proton-proton interactions at high energies, arXiv:1605.09176; J. L. Albacete, H. Petersen, A. Soto-Ontoso, Correlated wounded hot spots in proton-proton interactions, arXiv:1612.06274], we present a novel initial state geometry for proton-proton interactions. We rely on gluonic hot spots as effective degrees of freedom whose transverse positions inside the proton are correlated. We explore the impact of these non-trivial spatial correlations on the eccentricity and triangularity of the system following a Monte Carlo Glauber approach.
We present a systematic study on the influence of spatial correlations between the proton constituents, in our case gluonic hot spots, their size and their number on the symmetric cumulant SC(2,3), at the eccentricity level, within a Monte Carlo Glauber framework [J.L. Albacete, H. Petersen, A. Soto-Ontoso, Symmetric cumulants as a probe of the proton substructure at LHC energies, Phys. Lett. B778 (2018) 128–136. arXiv:1707.05592, doi:10.1016/j.physletb.2018.01.011]. When modeling the proton as composed by 3 gluonic hot spots, the most common assumption in the literature, we find that the inclusion of spatial correlations is indispensable to reproduce the negative sign of SC(2,3) in the highest centrality bins as dictated by data. Further, the subtle interplay between the different scales of the problem is discussed. To conclude, the possibility of feeding a 2+1D viscous hydrodynamic simulation with our entropy profiles is exposed.
Photofragmentation spectroscopy—the study of "half collisions" with polarized light of subdoppler line width—opens a window to look into the structure of molecules. The energy partitioning among the particular degrees of freedom of the products of the fragmentation reaction is described by the scalar properties, the direction and magnitude of a particular type of motion is described by the vector properties. The measurement of the scalar and vector properties allows a pictorial view of the intermediate state. The forces which make the fragments fly apart or rotate and vibrate can be "seen" from the line shapes. Information on the unstable intermediate state is gained from the stable fragments long after the dissociation of the parent molecule. In particular, information on the "lifetime" of the intermediate on a femtosecond time scale can be obtained.
A number of molecules, mainly three and four atomic, have been studied by this technique. Hydrogen peroxide has shown up as a textbook example. A complete analysis was possible including not only correlation of different types of fragment motion but also a correlation of the two coincident particles formed from the same parent molecule. The experimental results are in full agreement with recent calculations of the dynamics of the fragmentation on newly obtained potential energy surfaces. Hydrogen peroxide shows a strong dependence of its potential energy on the dihedral angle in the two electronic states amenable to laser excitation. This experiment further demonstrates that an analysis is also possible if two states are excited simultaneously.
Another good example is the fragmentation of hydrazoic acid for which also coincident pair correlation has been treated. Here again the results agree excellently with a qualitative picture which can be drawn from recently calculated ab initio potential energy surfaces. The HN3 example is much more complicated than the former one due to its higher structured upper potential energy surface. Strong rotational excitation is observed in the N2 fragment leaving the NH fragment rotationally cold.
The treatment of vector correlations in molecular photofragmentation is a powerful tool for the study of the dynamics of molecular dissociation reactions.