37,518 research outputs found
Wilson ratio of Fermi gases in one dimension
We calculate the Wilson ratio of the one-dimensional Fermi gas with spin
imbalance. The Wilson ratio of attractively interacting fermions is solely
determined by the density stiffness and sound velocity of pairs and of excess
fermions for the two-component Tomonaga-Luttinger liquid (TLL) phase. The ratio
exhibits anomalous enhancement at the two critical points due to the sudden
change in the density of states. Despite a breakdown of the quasiparticle
description in one dimension, two important features of the Fermi liquid are
retained, namely the specific heat is linearly proportional to temperature
whereas the susceptibility is independent of temperature. In contrast to the
phenomenological TLL parameter, the Wilson ratio provides a powerful parameter
for testing universal quantum liquids of interacting fermions in one, two and
three dimensions.Comment: 5+2 pages, 4+1 figures, Eq. (4) is proved, figures were refine
Universal local pair correlations of Lieb-Liniger bosons at quantum criticality
The one-dimensional Lieb-Liniger Bose gas is a prototypical many-body system
featuring universal Tomonaga-Luttinger liquid (TLL) physics and free fermion
quantum criticality. We analytically calculate finite temperature local pair
correlations for the strong coupling Bose gas at quantum criticality using the
polylog function in the framework of the Yang-Yang thermodynamic equations. We
show that the local pair correlation has the universal value in the quantum critical regime, the TLL phase and the
quasi-classical region, where is the pressure per unit length rescaled by
the interaction energy with interaction
strength and linear density . This suggests the possibility to test
finite temperature local pair correlations for the TLL in the relativistic
dispersion regime and to probe quantum criticality with the local correlations
beyond the TLL phase. Furthermore, thermodynamic properties at high
temperatures are obtained by both high temperature and virial expansion of the
Yang-Yang thermodynamic equation.Comment: 8 pages, 6 figures, additional text and reference
Comparison of traditional and genomic breeding programs for organic and low input dairy cattle accounting for traits relevant in different macro-climatic zones
In the past decade, successful selection on production traits for dairy cattle has greatly increased milk production. Recently, selection indices for female fertility were gradually and increasingly introduced into the overall breeding goals for dairy cattle (Miglior et al., 2005).
As a by-product of fermention in ruminants, enteric methane emissions (ME) should also be controlled and mitigated due to their contribution to global warming (Forster et al., 2007) and as a cause for inefficient use of dietary energy.
Moderate heritabilities ranging between 0.30 and 0.35 for predicted and real measurements of ME were reported for dairy cows and ewe lambs (de Haas et al., 2011; Pinares-Patiño et al., 2011), indicating that a heritable component for ME is available for implementing sustainable breeding strategies to reduce ME in dairy farms. In dairy cattle production systems, the traditional progeny testing substantially increases accuracy of selection especially for bulls.
However, availability of high-density SNP arrays enable dairy cattle breeders to apply genomic selection in their breeding strategies. Consequently, the objective of this study was to compare selection response for a complex breeding goal comprising ME, milk yield (MY), days open (DO), clinical mastitis (CM), body condition score (BCS) and milking temperament (MT) and total discounted return for organic and low input dairy cattle (with organic Brown Swiss as an example) from progeny testing and genomic breeding program by applying ZPLAN+ (Täubert et al., 2010)
Relation Embedding for Personalised POI Recommendation
Point-of-Interest (POI) recommendation is one of the most important
location-based services helping people discover interesting venues or services.
However, the extreme user-POI matrix sparsity and the varying spatio-temporal
context pose challenges for POI systems, which affects the quality of POI
recommendations. To this end, we propose a translation-based relation embedding
for POI recommendation. Our approach encodes the temporal and geographic
information, as well as semantic contents effectively in a low-dimensional
relation space by using Knowledge Graph Embedding techniques. To further
alleviate the issue of user-POI matrix sparsity, a combined matrix
factorization framework is built on a user-POI graph to enhance the inference
of dynamic personal interests by exploiting the side-information. Experiments
on two real-world datasets demonstrate the effectiveness of our proposed model.Comment: 12 pages, 3 figures, Accepted in the 24th Pacific-Asia Conference on
Knowledge Discovery and Data Mining (PAKDD 2020
High-energy kink in high-temperature superconductors
In conventional metals, electron-phonon coupling, or the phonon-mediated
interaction between electrons, has long been known to be the pairing
interaction responsible for the superconductivity. The strength of this
interaction essentially determines the superconducting transition temperature
TC. One manifestation of electron-phonon coupling is a mass renormalization of
the electronic dispersion at the energy scale associated with the phonons. This
renormalization is directly observable in photoemission experiments. In
contrast, there remains little consensus on the pairing mechanism in cuprate
high temperature superconductors. The recent observation of similar
renormalization effects in cuprates has raised the hope that the mechanism of
high temperature superconductivity may finally be resolved. The focus has been
on the low energy renormalization and associated "kink" in the dispersion at
around 50 meV. However at that energy scale, there are multiple candidates
including phonon branches, structure in the spin-fluctuation spectrum, and the
superconducting gap itself, making the unique identification of the excitation
responsible for the kink difficult. Here we show that the low-energy
renormalization at ~50 meV is only a small component of the total
renormalization, the majority of which occurs at an order of magnitude higher
energy (~350 meV). This high energy kink poses a new challenge for the physics
of the cuprates. Its role in superconductivity and relation to the low-energy
kink remains to be determined.Comment: 13 pages, 4 figure
Programming DNA Tube Circumferences
Synthesizing molecular tubes with monodisperse, programmable circumferences is an important goal shared by nanotechnology, materials science, and supermolecular chemistry. We program molecular tube circumferences by specifying the complementarity relationships between modular domains in a 42-base single-stranded DNA motif. Single-step annealing results in the self-assembly of long tubes displaying monodisperse circumferences of 4, 5, 6, 7, 8, 10, or 20 DNA helices
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