1,420 research outputs found
What about their performance do free jazz improvisers agree upon? A case study
When musicians improvise freely together—not following any sort of script, predetermined harmonic structure, or “referent”—to what extent do they understand what they are doing in the same way as each other? And to what extent is their understanding privileged relative to outside listeners with similar levels of performing experience in free improvisation? In this exploratory case study, a saxophonist and a pianist of international renown who knew each other's work but who had never performed together before were recorded while improvising freely for 40 min. Immediately afterwards the performers were interviewed separately about the just-completed improvisation, first from memory and then while listening to two 5 min excerpts of the recording in order to prompt specific and detailed commentary. Two commenting listeners from the same performance community (a saxophonist and drummer) listened to, and were interviewed about, these excerpts. Some months later, all four participants rated the extent to which they endorsed 302 statements that had been extracted from the four interviews and anonymized. The findings demonstrate that these free jazz improvisers characterized the improvisation quite differently, selecting different moments to comment about and with little overlap in the content of their characterizations. The performers were not more likely to endorse statements by their performing partner than by a commenting listener from the same performance community, and their patterns of agreement with each other (endorsing or dissenting with statements) across multiple ratings—their interrater reliability as measured with Cohen's kappa—was only moderate, and not consistently higher than their agreement with the commenting listeners. These performers were more likely to endorse statements about performers' thoughts and actions than statements about the music itself, and more likely to endorse evaluatively positive than negative statements. But these kinds of statements were polarizing; the performers were more likely to agree with each other in their ratings of statements about the music itself and negative statements. As in Schober and Spiro (2014), the evidence supports a view that fully shared understanding is not needed for joint improvisation by professional musicians in this genre and that performing partners can agree with an outside listener more than with each other
Enzymatic reactions towards aldehydes: An overview
Many aldehydes are volatile compounds with distinct and characteristic olfactory properties. The aldehydic functional group is reactive and, as such, an invaluable chemical multi-tool to make all sorts of products. Owing to the reactivity, the selective synthesis of aldehydic is a challenging task. Nature has evolved a number of enzymatic reactions to produce aldehydes, and this review provides an overview of aldehyde-forming reactions in biological systems and beyond. Whereas some of these biotransformations are still in their infancy in terms of synthetic applicability, others are developed to an extent that allows their implementation as industrial biocatalysts
Crystal-like high frequency phonons in the amorphous phases of solid water
The high frequency dynamics of low- (LDA) and high-density amorphous-ice
(HDA) and of cubic ice (I_c) has been measured by inelastic X-ray Scattering
(IXS) in the 1-15 nm^{-1} momentum transfer (Q) range. Sharp phonon-like
excitations are observed, and the longitudinal acoustic branch is identified up
to Q = 8nm^{-1} in LDA and I_c and up to 5nm^{-1} in HDA. The narrow width of
these excitations is in sharp contrast with the broad features observed in all
amorphous systems studied so far. The "crystal-like" behavior of amorphous
ices, therefore, implies a considerable reduction in the number of decay
channels available to sound-like excitations which is assimilated to low local
disorder.Comment: 4 pages, 3 figure
Interatomic-Coulombic-decay-induced recapture of photoelectrons in helium dimers
We investigate the onset of photoionization shakeup induced interatomic
Coulombic decay (ICD) in He2 at the He+*(n = 2) threshold by detecting two He+
ions in coincidence. We find this threshold to be shifted towards higher
energies compared to the same threshold in the monomer. The shifted onset of
ion pairs created by ICD is attributed to a recapture of the threshold
photoelectron after the emission of the faster ICD electron.Comment: 5 Pages, 2 Figure
A measurement of the evolution of Interatomic Coulombic Decay in the time domain
During the last 15 years a novel decay mechanism of excited atoms has been
discovered and investigated. This so called ''Interatomic Coulombic Decay''
(ICD) involves the chemical environment of the electronically excited atom: the
excitation energy is transferred (in many cases over long distances) to a
neighbor of the initially excited particle usually ionizing that neighbor. It
turned out that ICD is a very common decay route in nature as it occurs across
van-der-Waals and hydrogen bonds. The time evolution of ICD is predicted to be
highly complex, as its efficiency strongly depends on the distance of the atoms
involved and this distance typically changes during the decay. Here we present
the first direct measurement of the temporal evolution of ICD using a novel
experimental approach.Comment: 6 pages, 4 figures, submitted to PR
Vibrationally Resolved Decay Width of Interatomic Coulombic Decay in HeNe
We investigate the ionization of HeNe from below the He 1s3p excitation to
the He ionization threshold. We observe HeNe ions with an enhancement by
more than a factor of 60 when the He side couples resonantly to the radiation
field. These ions are an experimental proof of a two-center resonant
photoionization mechanism predicted by Najjari et al. [Phys. Rev. Lett. 105,
153002 (2010)]. Furthermore, our data provide electronic and vibrational state
resolved decay widths of interatomic Coulombic decay (ICD) in HeNe dimers. We
find that the ICD lifetime strongly increases with increasing vibrational
state.Comment: 7 pages, 5 figure
Ice XII in its second regime of metastability
We present neutron powder diffraction results which give unambiguous evidence
for the formation of the recently identified new crystalline ice phase[Lobban
et al.,Nature, 391, 268, (1998)], labeled ice XII, at completely different
conditions. Ice XII is produced here by compressing hexagonal ice I_h at T =
77, 100, 140 and 160 K up to 1.8 GPa. It can be maintained at ambient pressure
in the temperature range 1.5 < T < 135 K. High resolution diffraction is
carried out at T = 1.5 K and ambient pressure on ice XII and accurate
structural properties are obtained from Rietveld refinement. At T = 140 and 160
K additionally ice III/IX is formed. The increasing amount of ice III/IX with
increasing temperature gives an upper limit of T ~ 150 K for the successful
formation of ice XII with the presented procedure.Comment: 3 Pages of RevTeX, 3 tables, 3 figures (submitted to Physical Review
Letters
Sparse random matrices and vibrational spectra of amorphous solids
A random matrix approach is used to analyze the vibrational properties of
amorphous solids. We investigated a dynamical matrix M=AA^T with non-negative
eigenvalues. The matrix A is an arbitrary real NxN sparse random matrix with n
independent non-zero elements in each row. The average values =0 and
dispersion =V^2 for all non-zero elements. The density of vibrational
states g(w) of the matrix M for N,n >> 1 is given by the Wigner quarter circle
law with radius independent of N. We argue that for n^2 << N this model can be
used to describe the interaction of atoms in amorphous solids. The level
statistics of matrix M is well described by the Wigner surmise and corresponds
to repulsion of eigenfrequencies. The participation ratio for the major part of
vibrational modes in three dimensional system is about 0.2 - 0.3 and
independent of N. Together with term repulsion it indicates clearly to the
delocalization of vibrational excitations. We show that these vibrations spread
in space by means of diffusion. In this respect they are similar to diffusons
introduced by Allen, Feldman, et al., Phil. Mag. B 79, 1715 (1999) in amorphous
silicon. Our results are in a qualitative and sometimes in a quantitative
agreement with molecular dynamic simulations of real and model glasses.Comment: 24 pages, 7 figure
Absence of molecular mobility on nano-second time scales in amorphous ice phases
High-resolution neutron backscattering techniques are exploited to study the
elastic and quasi-elastic response of the high-density amorphous (HDA), the
low-density amorphous (LDA) and the crystalline ice Ic upon temperature
changes. Within the temperature ranges of their structural stability (HDA at T
> 80 K, LDA at T > 135 K, ice Ic at T < 200 K) the Debye-Waller factors and
mean-square displacements characterise all states as harmonic solids. During
the transformations HDA->LDA (T ~ 100 K), LDA->Ic (T ~ 150K) and the supposed
glass transition with Tg ~ 135 K no relaxation processes can be detected on a
time scale t < 4 ns. It can be concluded from coherent scattering measurements
(D_2O) that LDA starts to recrystallise into ice Ic at T ~ 135 K, i.e. at the
supposed Tg. In the framework of the Debye model of harmonic solids HDA reveals
the highest Debye temperature among the studied ice phases, which is in full
agreement with the lowest Debye level in the generalised density of states
derived from time-of-flight neutron scattering experiments. The elastic results
at low T indicate the presence of an excess of modes in HDA, which do not obey
the Bose statistics
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