1,835 research outputs found
Early Life Relict Feature in Peptide Mass Distribution
Molecular mass of a biomolecule is characterized in mass spectroscopy by the monoisitopic mass M~mono~ and the average isotopic mass M~av~. We found that peptide masses mapped on a plane made by two parameters derived from M~mono~ and M~av~ form a peculiar global feature in form of a band-gap 5-7 ppm wide stretching across the whole peptide galaxy, with a narrow (FWHM 0.2 ppm) line in the centre. The a priori probability of such a feature to emerge by chance is less than 1:100. Peptides contributing to the central line have elemental compositions following the rules S=0; Z = (2C - N - H)/2 =0, which nine out of 20 amino acid residues satisfy. The relative abundances of amino acids in the peptides contributing to the central line correlate with the consensus order of emergence of these amino acids, with ancient amino acids being overrepresented in on-line peptides. Thus the central line is a relic of ancient life, and likely a signature of its emergence in abiotic synthesis. The linear correlation between M~av~ and M~mono~ reduces the complexity of polypeptide molecules, which may have increased the rate of their abiotic production. This, in turn may have influenced the selection of these amino acid residues for terrestrial life. Assuming the line feature is not spurious, life has emerged from elements with isotopic abundances very close to terrestrial levels, which rules out most of the Galaxy
Extrapolated High-Order Propagators for Path Integral Monte Carlo Simulations
We present a new class of high-order imaginary time propagators for
path-integral Monte Carlo simulations by subtracting lower order propagators.
By requiring all terms of the extrapolated propagator be sampled uniformly, the
subtraction only affects the potential part of the path integral. The
negligible violation of positivity of the resulting path integral at small time
steps has no discernable affect on the accuracy of our method. Thus in
principle arbitrarily high order algorithms can be devised for path-integral
Monte Carlo simulations. We verify this claim is by showing that fourth, sixth,
and eighth order convergence can indeed be achieved in solving for the ground
state of strongly interacting quantum many-body systems such as bulk liquid
He.Comment: 9 pages and 3 figures. Submitted to J. Chem. Phy
Mind the (gender) gap: Gender, gender role types, and their effects on objective career success over time
Drawing on ideas by Pierre Bourdieu, this paper analyzes the effects of gender and gender role type (GRT) for objective career success (i.e., income) over time. Empirically, data from two cohorts of business school graduates were analyzed with mixed linear models. Gender and GRT, both perceived as career capital, progressively affect objective career success over time, with feminine GRT hampering objective career success for both sexes. Remaining results vary between the two cohorts: findings for the younger cohort deviate more strongly from the hypotheses derived
Towards predictive modelling of near-edge structures in electron energy loss spectra of AlN based ternary alloys
Although electron energy loss near edge structure analysis provides a tool
for experimentally probing unoccupied density of states, a detailed comparison
with simulations is necessary in order to understand the origin of individual
peaks. This paper presents a density functional theory based technique for
predicting the N K-edge for ternary (quasi-binary) nitrogen alloys by adopting
a core hole approach, a methodology that has been successful for binary nitride
compounds. It is demonstrated that using the spectra of binary compounds for
optimising the core hole charge ( for cubic TiAlN
and for wurtzite AlGaN), the predicted spectra
evolutions of the ternary alloys agree well with the experiments. The spectral
features are subsequently discussed in terms of the electronic structure and
bonding of the alloys.Comment: 11 pages, 9 figures, 1 tabl
World caf\ue9 method to engage smart energy-district project partners in assessing urban co-benefits
Urban energy-district projects introduce outstanding technological innovation in buildings and energy systems increasing sustainability in city neighborhoods. Such projects generate additional co-benefits for the city beyond changes in physical elements and development of social and institutional relationships (e.g. local employment, environmental quality, public health, property values, innovation attitude, etc.). Since exceeding main declared goals or not always clearly foreseen in the early project phase, these co-benefits are often not properly understood and considered. However, only their explicit recognition will make possible their inclusion in the assessment of the whole project\u2019s performance. From these considerations, this study faces the issue of engaging project partners in assessing co-benefits in order to consider a broad spectrum of relevant, positive effects in the evaluation process. Group knowledge and group thinking of this complex topic are investigated through the world caf\ue9 method, providing an atmosphere of trust and open discussions among participants. This empirical work lays the foundations to go beyond the mere economic measure as the sole criterion for assessing project effects, also including changes in end-user behavior and intangible asset
Notes on Amandinea Petermannii Comb.nov. (Physciaceae) from Antarctica
The new combination Amandinea petermannii (Hue) Matzer, Mayrh. & Scheidegger; is proposed. The taxonomy, morphology, anatomy, chemistry, ecology and distribution of this lichen are discussed. Rinodina convoluta D. C. Lindsay is synonym of A. petermanni
Macroscopic Elastic Properties of Textured ZrN--AlN Polycrystalline Aggregates: From Ab initio Calculations to Grain-Scale Interactions
Despite the fast development of computational materials modelling,
theoretical description of macroscopic elastic properties of textured
polycrystalline aggregates starting from basic principles remains a challenging
task. In this communication we use a supercell-based approach to obtain the
elastic properties of random solid solution cubic ZrAlN system as a function of
the metallic sublattice composition and texture descriptors. The employed
special quasi-random structures are optimised not only with respect to short
range order parameters, but also to make the three cubic directions
, , and as similar as possible. In this way,
only a small spread of elastic constants tensor components is achieved and an
optimum trade-off between modelling of chemical disorder and computational
limits regarding the supercell size is achieved. The single crystal elastic
constants are shown to vary smoothly with composition, yielding
-0.5 an alloy constitution with an almost isotropic response.
Consequently, polycrystals with this composition are suggested to have Young's
modulus independent on the actual microstructure. This is indeed confirmed by
explicit calculations of polycrystal elastic properties, both within the
isotropic aggregate limit, as well as with fibre textures with various
orientations and sharpness. It turns out, that for low AlN mole fractions, the
spread of the possible Young's moduli data caused by the texture variation can
be larger than 100 GPa. Consequently, our discussion of Young's modulus data of
cubic ZrAlN contains also the evaluation of the texture typical for thin films.Comment: 10 pages, 6 figures, 3 table
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A synthesis: what works to deliver optimal health outcomes for uk care home residents
The detailed reviews, interviews and subsequent longitudinal case studies structured around a unifying realist analytical framework allowed us to establish a theory of commissioning for health care provision to care homes which proposes health services will work better when: staff are explicitly tasked to work with care homes at an institutional level as well as individual residents; healthcare and care home staff are empowered to co-design their working models; where explicit expertise in dementia care is available; the role of GP as a medical care provider is supported by access to a wider array of services; and they incorporate care management. There was no evidence from our study that a short term focus on avoiding admissions to acute hospitals from care homes added any value to service specification or care delivery
Surface Structure of Bi(111) from Helium Atom Scattering Measurements. Inelastic Close-Coupling Formalism
8 págs.; 4 figs.; 2 tabs.; Open Access funded by Creative Commons Atribution Licence 4.0© 2015 American Chemical Society. Elastic and inelastic close-coupling (CC) calculations have been used to extract information about the corrugation amplitude and the surface vibrational atomic displacement by fitting to several experimental diffraction patterns. To model the three-dimensional interaction between the He atom and the Bi(111) surface under investigation, a corrugated Morse potential has been assumed. Two different types of calculations are used to obtain theoretical diffraction intensities at three surface temperatures along the two symmetry directions. Type one consists of solving the elastic CC (eCC) and attenuating the corresponding diffraction intensities by a global Debye-Waller (DW) factor. The second one, within a unitary theory, is derived from merely solving the inelastic CC (iCC) equations, where no DW factor is necessary to include. While both methods arrive at similar predictions for the peak-to-peak corrugation value, the variance of the value obtained by the iCC method is much better. Furthermore, the more extensive calculation is better suited to model the temperature induced signal asymmetries and renders the inclusion for a second Debye temperature for the diffraction peaks futile.This research was supported by the European Commission and
the Styrian Government within the ERDF program. S.M.A.
acknowledges MICINN (Spain) through Grant No. FIS2011-
29596-C02-01. A.T. acknowledges financial support provided
by the FWF (Austrian Science Fund) within the project J3479-
N20.Peer Reviewe
Rational F-Theory GUTs without exotics
We construct F-theory GUT models without exotic matter, leading to the MSSM
matter spectrum with potential singlet extensions. The interplay of engineering
explicit geometric setups, absence of four-dimensional anomalies, and realistic
phenomenology of the couplings places severe constraints on the allowed local
models in a given geometry. In constructions based on the spectral cover we
find no model satisfying all these requirements. We then provide a survey of
models with additional U(1) symmetries arising from rational sections of the
elliptic fibration in toric constructions and obtain phenomenologically
appealing models based on SU(5) tops. Furthermore we perform a bottom-up
exploration beyond the toric section constructions discussed in the literature
so far and identify benchmark models passing all our criteria, which can serve
as a guideline for future geometric engineering.Comment: 27 Pages, 1 Figur
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