Incidence and Risk Factors of Neoplastic Progression in Barrett’s Esophagus

Barrett’s esophagus (BE) is a condition in which the normal stratified squamous epithelium lining the distal esophagus is replaced by columnar epithelium with specialized intestinal metaplasia (IM) containing goblet cells. The development of BE is a complication of chronic exposure to the gastric refluxate containing acid and bile.1-3 BE is a premalignant condition which predisposes to the development of esophageal adenocarcinoma (EAC). The development of this malignancy is a gradual stepwise process from no dysplasia (ND) to low-grade dysplasia (LGD), high-grade dysplasia (HGD), and finally EAC. During the past decades, the incidence of both BE5 and EAC has been rising rapidly as demonstrated by a 7-fold increased incidence of EAC between 1973 and 2006.6-8 In general, patients with BE have a 30- to 125-fold increased risk of developing EAC compared to the general population. However, the annual incidence of EAC in BE patients remains unclear, as it shows considerable variation among cohort studies, ranging from 0.2% to almost 3.5% per year. The consensus is however that the incidence of EAC is approximately 0.5% per year.13 EAC usually has a poor prognosis and a high mortality with a 5-year survival rate of less than 20%. As a result of the malignant potential of BE, regular surveillance endoscopies are recommended in patients with BE. The intervals of surveillance depend on the grade of dysplasia present. The goal of surveillance is to detect neoplasia at an early stage, making early treatment with curative intention possible and reducing death from EAC

Phase Transitions in the One-Dimensional Pair-Hopping Model: a Renormalization Group Study

The phase diagram of a one-dimensional tight-binding model with a pair-hopping term (amplitude V) has been the subject of some controvery. Using two-loop renormalization group equations and the density matrix renormalization group with lengths L<=60, we argue that no spin-gap transition occurs at half-filling for positive V, contrary to recent claims. However, we point out that away from half-filling, a *phase-separation* transition occurs at finite V. This transition and the spin-gap transition occuring at half-filling and *negative* V are analyzed numerically.Comment: 7 pages RevTeX, 6 uuencoded figures which can be (and by default are) directly included. Received by Phys. Rev. B 20 April 199

Contractional Cornucopia on Offshore Angola

Three main contractional tectonic regimes are recognized: (1) Late Cretaceous gravity spreading, (2) Mid-Tertiary uplift, and (3) Neogene transpression. Tilting of the young continental margin created the first tectonic regime, the ultimate cause of this was thermal subsidence after continental breakup. The second regime was the direct cause of the uplift of the Angolan coast, mostly in the Oligo-Miocene but continuing into the Plio- Pleistocene, while the late tectonic regime was probably the differential movement of reactivated crustal blocks, whose slip directions depended on their orientation

Contractional Cornucopia on Offshore Angola

Three main contractional tectonic regimes are recognized: (1) Late Cretaceous gravity spreading, (2) Mid-Tertiary uplift, and (3) Neogene transpression. Tilting of the young continental margin created the first tectonic regime, the ultimate cause of this was thermal subsidence after continental breakup. The second regime was the direct cause of the uplift of the Angolan coast, mostly in the Oligo-Miocene but continuing into the Plio- Pleistocene, while the late tectonic regime was probably the differential movement of reactivated crustal blocks, whose slip directions depended on their orientation

Theory of Unconventional Spin Density Wave: A Possible Mechanism of the Micromagnetism in U-based Heavy Fermion Compounds

We propose a novel spin density wave (SDW) state as a possible mechanism of the anomalous antiferromagnetism, so-called the micromagnetism, in URu_2Si_2 below 17.5[K]. In this new SDW, the electron-hole pair amplitude changes its sign in the momentum space as in the case of the unconventional superconductivity. It is shown that this state can be realized in an extended Hubbard model within the mean field theory. We also examine some characteristic properties of this SDW to compare with the experimental results. All these properties well explain the unsolved problem of the micromagnetism.Comment: REVTeX v3.1, 4 pages, 5 figure

Spin Gap in a Doped Kondo Chain

We show that the Kondo chain away from half-filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak-Kondo-coupling limit of the Heisenberg-Kondo lattice model by bosonization and in the strong-coupling limit by a mapping to a modified t-J model. Only for certain ranges of filling and Heisenberg coupling does the spin gap phase extend from weak to strong coupling.Comment: 4 pages RevTeX including 4 eps figures; minor corrections and clarification

Spin, Charge and Quasiparticle Gaps in the One-Dimensional Kondo Lattice with f^2 Configuration

The ground state properties of the one-dimensional Kondo lattice with an f^2 configuration at each site are studied by the density matrix renormalization group method. At half-filling, competition between the Kondo exchange J and the antiferromagnetic intra f-shell exchange I leads to reduction of energy gaps for spin, quasi-particle and charge excitations. The attractive force among conduction electrons is induced by the competition and the bound state is formed. As J/I increases the f^2 singlet gives way to the Kondo singlet as the dominant local correlation. The remarkable change of the quasi-particle gap is driven by the change of the spin-1/2 excitation character from the itinerant one to the localized one. Possible metal-insulator transition is discussed which may occur as the ratio J/I is varied by reference to mean-field results in the f^2 lattice system and the two impurity Kondo system.Comment: 7 pages, 7 figures, submitted to J. Phys. Soc. Jp