다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Statistical physics has proven to be a fruitful framework to describe phenomena outside the realm of traditional physics. Recent years have witnessed an attempt by physicists to study collective phenomena emerging from the interactions of individuals as elementary units in social structures. A wide list of topics are reviewed ranging from opinion and cultural and language dynamics to crowd behavior, hierarchy formation, human dynamics, and social spreading. The connections between these problems and other, more traditional, topics of statistical physics are highlighted. Comparison of model results with empirical data from social systems are also emphasized.

Statistical physics of social dynamics

We have studied the three quark system in a relativized version of the quark potential model with chromodynamics. With parameters consistent with those of an analogous study of meson spectroscopy we obtain a successful description of the spectrum of baryons. The model naturally explains the apparent absence of spin‐orbit interactions in baryons.

Baryons in a relativized quark model with chromodynamics

Monthly Notices is one of the three largest general primary astronomical research publications. It is an international journal, published by the Royal Astronomical Society. This article 1 describes its publication policy and practice.

Monthly Notices of the Royal Astronomical Society

The helicity-dependent strange quark distribution in the proton, Δ s , is calculated in a nonlocal chiral SU(3) effective field theory. The hadronic proton to meson plus octet or decuplet baryon splitting functions are derived at the one-loop level, with loop integrals rendered finite by correlation functions introduced in the nonlocal Lagrangian. Within the convolution framework, the proton strange helicity distribution is obtained using spin-flavor symmetry to constrain the input valence quark distributions in the hadronic intermediate states. The polarized strange quark distribution is found to be quite small, with the lowest moment of Δ s negative, but consistent with recent global QCD analyses. for the interaction between a strange quark s and an external axial-vector field in the corresponding hadronic configurations.

Helicity-dependent distribution of strange quarks in the proton from nonlocal chiral effective theory

Perhaps the most profound question in nuclear physics is the extent to which the internal structure of the nucleon matters in microscopic calculations of phenomena such as the N-N force, nuclear binding energies and densities and the response of nuclei to weak and electromagnetic probes. In answering it we would forge a long needed link between high energy and nuclear physics. My own interest in the problem is over a decade old, beginning with naive considerations of size based on the MIT bag model and its chiral extensions, notably the cloudy bag model. From such a beginning it is possible to take two divergent paths. The first is to ask what constraints more elementary, phenomenological considerations can put on the structure of the nucleon and therefore on the existing QCD-motivated models. The second is to ask how the consequences of different models might vary for the phenomena mentioned.

Probing the Quark Structure of Matter

The positive-parity nucleon spectrum is studied in 2 + 1 flavour lattice QCD in an attempt to discover novel low-lying energy eigenstates in the region of the Roper resonance. In this work, we employ standard three-quark interpolating fields and introduce new local five-quark meson-baryon operators that hold the possibility of revealing new states that have been missed in previous studies. Motivated by phenomenological arguments, five-quark interpolators based on the $\sigma{N}$, $\pi{N}$ and $a_0{N}$ channels are constructed. Despite the introduction of qualitatively different operators, no novel energy levels are extracted near the regime of the Roper resonance.

Spectroscopy with Local Multi-hadron Interpolators in Lattice QCD

Corrections motivated by chiral symmetry arguments have long been known to give important contributions to hadronic observables, particularly at low momentum transfer. It is possible to separate these approaches into two broad groups; either the corrections are implemented at the parton level, or at the hadron level. We explore the results of incorporating pion loop corrections at the hadron level to a calculation of electromagnetic form factors in the NJL model. These calculations are compared with the result of an earlier implementation of pion loops at the parton level using the same NJL model formalism. A particular parameter set yields a good description of low energy nucleon properties within both approaches. However, for the $\Sigma^-$ there is a remarkable improvement when the chiral corrections are implemented at the hadronic level.

Chiral Corrections to Baryon Electromagnetic Form Factors

The Stock Market is a complex self-interacting system, characterized by an intermittent behaviour. Periods of high activity alternate with periods of relative calm. In the present work we investigate empirically about the possibility that the market is in a self-organized critical state (SOC). A wavelet transform method is used in order to separate high activity periods, related to the avalanches of sandpile models, from quiescent. A statistical analysis of the filtered data show a power law behaviour in the avalanche size, duration and laminar times. The memory process, implied by the power law distribution, of the laminar times is not consistent with classical conservative models for self-organized criticality. We argue that a ``near-SOC'' state or a time dependence in the driver, which may be chaotic, can explain this behaviour.

Anthony W. Thomas

Papers

Helicity-dependent distribution of strange quarks in the proton from nonlocal chiral effective theory

Probing the Quark Structure of Matter

Spectroscopy with Local Multi-hadron Interpolators in Lattice QCD

Chiral Corrections to Baryon Electromagnetic Form Factors

Self-Organized Criticality and Stock Market Dynamics: an Empirical Study